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CURT 23521 Black Trailer Tongue Coupler Lock, 1/4-Inch Pin Diameter, Up to 3/4-Inch Span

4.5 4.5 out of 5 stars 2,151 ratings

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Purchase options and add-ons

  • DEPENDABLE SECURITY. To help protect your trailer from theft, this trailer lock is made from high-strength steel and has a padlock-style design
  • EASY TO OPERATE. This padlock-style trailer tongue lock has a heavy-duty look to deter theft, and uses a simple 1/4-turn lock activation for convenient locking and unlocking as needed
  • VERSATILE. With a 1/4-inch diameter pin, this trailer coupler lock fits latch-type couplers with a maximum span of up to 3/4 inches
  • WEATHER-RESISTANT. This trailer pin lock is protected from the elements with its black painted finish, while the coupler pin is shielded against corrosion with a durable zinc plating
  • TWO KEYS INCLUDED. For your convenience, two keys are included with this trailer tongue lock. You can keep the spare key in a discrete location for emergencies or give it to a friend for helpful access
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From the manufacturer

CURT Towing Accessories

Wherever your work or play takes you

CURT offers custom trailer hitches, electrical products and a complete line of towing accessories to get you there with confidence and enjoy every mile of the journey.

CURT Trailer Hitches Camper RV Jeep Towing

Towing accessories to fit your lifestyle

Hitches, trailer wiring, cargo carriers and more!

CURT offers a complete line of towing accessories to let you fully enjoy your passion!

With everything from custom trailer hitches and trailer wiring to 5th wheel hitches and cargo carriers, we have the towing equipment you need to make the most of each adventure.

Whether you're working, playing or doing a little of both, CURT towing products enable you and your crew to make memories that will last a lifetime.

A complete line of towing products

  • Trailer hitches
  • 5th wheel hitches
  • Gooseneck hitches
  • Towing electrical
  • Towing accessories
  • Weight distribution
  • Trailer parts and accessories
  • Cargo management

Basic towing components

CURT Trailer Hitch Towing Accessories Ball Mount

CURT Custom Trailer Wiring Harness Hitch Receiver

CURT Ball Hitch Mount Towing Accessories

CURT Hitch Cargo Carrier Cargo Net

Custom hitches

A trailer hitch receiver is the starting point for most people looking to tow with their vehicle. CURT offers over 1,000 different custom hitch models to provide a perfect, factory-like fit on most vehicles on the road today. Our custom hitches provide a standard hitch receiver to mount a variety of towing accessories.

Vehicle-trailer wiring

The next step in equipping your vehicle for towing is to add a trailer wiring harness. Like our hitches, CURT custom wiring is made vehicle-specific for each make and model. Virtually all of our custom vehicle-trailer wiring harnesses install using existing factory connectors on the vehicle for a plug-and-play connection. No splicing necessary!

Ball mounts

With a custom trailer hitch receiver installed on your vehicle, a variety of ball mount options can be installed as needed. We offer loaded ball mounts with a trailer ball already torqued in place, as well as adjustable ball mounts, multi-ball mounts, tow hooks and more. A ball mount can be secured into the receiver using one of our hitch pins or hitch locks.

Cargo management

To add cargo space to your vehicle, CURT offers a number of cargo management accessories. Our cargo carriers are available in a convenient, use-as-needed hitch-mounted design, as well as a roof rack option. We also offer bike racks, cargo bags, cargo nets and ratchet straps for additional item security.

Heavy-duty towing equipment

CURT 5th Wheel Hitch Truck Bed Towing

CURT Gooseneck Hitch OEM Puck System Truck Bed

CURT Echo Mobile Electric Trailer Brake Controller Smartphone

5th wheel hitches

For heavy-duty towing of an RV or travel trailer with your pickup truck, CURT has a wide array of 5th wheel hitch options. 5th wheel hitches are available in capacities up to 25,000 lbs. and in various series, each with own unique set of features and benefits. To install a 5th wheel hitch in your pickup truck bed, CURT offers traditional 5th wheel rails and brackets, as well as puck system options and gooseneck adapters.

Gooseneck hitches

For towing heavy-duty trailers around the farm or out to the construction site, CURT gooseneck hitches are a highly dependable extension of your truck. We offer puck system gooseneck hitch kits to accommodate trucks with the factory towing prep package. We also offer original-equipment-style gooseneck hitches for select applications, as well as traditional gooseneck hitches and brackets, such as our original Double Lock.

Trailer brake controllers

CURT offers several different electrical trailer brake controller options to perfectly suit your towing setup and lifestyle. Our Echo mobile trailer brake controller is particularly unique, featuring a Bluetooth connection that links to your smartphone and provides highly responsive braking with your Apple or Android device as the interface. It easily plugs in with no tools or extra wires needed. We also offer our factory-like Spectrum and traditional TriFlex.

Specialized towing accessories

CURT Trailer Hitch Adjustable Channel Mount

CURT Weight Distribution Hitch Trailer Sway Control

CURT Pintle Hitch Mount Lunette Ring

CURT Cargo Ratchet Straps Trailer Truck Towing

Adjustable channel mounts

To give your vehicle greater capability for towing a variety of trailers, CURT adjustable trailer hitch ball mounts provide the answer. This versatile ball hitch comes in standard hitch receiver sizes and provides flexible vertical adjustment to ensure level towing, even with large, lifted trucks and SUVs.

Weight distribution hitches

Give yourself more control over your vehicle and trailer with a CURT weight distribution hitch. This receiver hitch attachment helps level the vehicle-trailer combination for a smoother ride. Our TruTrack weight distribution hitch is particularly unique, featuring integrated trailer sway control.

Pintle hitches

These heavy-duty hitches are perfect for agriculture, construction and military towing. We offer pintle hitches, pintle hooks, ball and pintle hitch combinations, as well as channel-mount pintle hitches for an adjustable option. We also carry high-strength lunette rings for a solid connection to the trailer.

Ratchet straps

Keep your cargo fully secure in your truck bed or trailer with a set of CURT ratchet straps. These cargo tie-down straps come with heavy-duty ratcheting mechanisms and are available in wide variety of capacities, lengths, hook types and colors.

Product Description

Sometimes a safety pin and coupler latch are just not enough to keep your toys safe. While CURT safety pins and coupler latches are made to keep your coupler securely latched onto your trailer ball, they are no substitute for the locking power provided by a CURT coupler lock. CURT coupler locks are designed to add security to your trailer and towing equipment. Instead of merely retaining the coupler latch mechanism, they lock it into place and greatly deter any tampering and theft of your trailer while it is coupled to your vehicle. CURT coupler locks are key-operated and come in several different styles for you to choose from. This coupler lock features a padlock design to keep the pin well protected from tampering. It comes with a black finish and offers a pin span of 3/4" with a pin diameter of 1/4". All CURT coupler locks are made to fit latch-type couplers and include two keys. Protect your boat, your camper and even your utility trailer the right way with a CURT coupler lock.

Product information

Technical Details

Additional Information

Warranty & Support

Amazon.com Return Policy:Amazon.com Voluntary 30-Day Return Guarantee: You can return many items you have purchased within 30 days following delivery of the item to you. Our Voluntary 30-Day Return Guarantee does not affect your legal right of withdrawal in any way. You can find out more about the exceptions and conditions here.
Manufacturer’s warranty can be requested from customer service. Click here to make a request to customer service.

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CURT 23521 Black Trailer Tongue Coupler Lock, 1/4-Inch Pin Diameter, Up to 3/4-Inch Span


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What's in the box

  • 1 LOCK, BLACK, 7/8" SPAN COUPLER
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    CURT 23521 Black Trailer Tongue Coupler Lock, 1/4-Inch Pin Diameter, Up to 3/4-Inch Span
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    Price$15.72$18.99$12.99$6.89$39.99-33% $9.99
    List:$14.99
    Delivery
    Get it as soon as Tuesday, Apr 2
    Get it as soon as Tuesday, Apr 2
    Get it as soon as Tuesday, Apr 2
    Get it as soon as Tuesday, Apr 2
    Get it as soon as Tuesday, Apr 2
    Get it as soon as Tuesday, Apr 2
    Customer Ratings
    Value for money
    4.7
    4.1
    4.2
    4.1
    4.4
    Easy to use
    4.2
    4.2
    4.0
    4.2
    4.3
    Easy to lock
    4.2
    4.0
    4.2
    4.2
    Sturdiness
    4.0
    4.1
    4.6
    Easy to install
    4.4
    4.4
    4.3
    Sold By
    Amazon.com
    Partner Co., Ltd.
    BISON TOOL
    Partner Co., Ltd.
    BISON TOOL
    BISON TOOL

    Looking for specific info?

    Customer reviews

    4.5 out of 5 stars
    4.5 out of 5
    2,151 global ratings

    Customers say

    Customers like the performance, ease of use, and value of the auto accessory. For example, they mention it works well, is effective, and easy to install and take off. That said, opinions are mixed on quality and fit.

    AI-generated from the text of customer reviews

    54 customers mention47 positive7 negative

    Customers like the performance of the coupler lock. For example, they say it's effective, easy to use, and gets the job done. Some mention that it'll deter others from messing with their trailer. Overall, most are happy with the performance and functionality of the product.

    "...I've decided to purchase a new one. Good price and works well." Read more

    "Works great! Screws down for a secure lock" Read more

    "...Better than a standard coupler which can be easily removed. It works great. Stick the key in and screw it on or off before removing...." Read more

    "...Works well and is built well for what it is." Read more

    35 customers mention32 positive3 negative

    Customers find the hitch lock easy to install and remove. They say it's simple and secure. Customers also mention that it'll unobtrusive and difficult for bad guys to remove.

    "...The hitch lock was simple to use and I felt it was more secure than just a pad lock since the diameter of the standard hole only allows a small..." Read more

    "Quality product and simple to use for keeping your trailer secure...." Read more

    "Nice quality lock. Easy to use." Read more

    "I bought this lock in August and it was easy to use the first couple of times while the trailer was in and out of storage for cleaning and prep...." Read more

    17 customers mention17 positive0 negative

    Customers appreciate the value of the auto accessory. They say it's a great lock for the price and an excellent purchase for any trailer.

    "...I've decided to purchase a new one. Good price and works well." Read more

    "...I highly recommend this lock, it was a good price, as well." Read more

    "I think overall the Curt products are good and priced fairly...." Read more

    "good value, well made, easy installation" Read more

    5 customers mention5 positive0 negative

    Customers are satisfied with the appearance of the auto accessory. They mention that it has a nice finish and looks new after 4 months.

    "...This one fits perfectly on the trailer coupler and looks nice. A lightweight popup trailer can be moved by hand so it’s vulnerable to theft...." Read more

    "...The lock has a nice finish. It should deter any spur of the moment type of theft." Read more

    "Loved the look, fit, and functionality of this product right away.On the 3rd use, the lock mechanism failed...." Read more

    "Love the design. Compact and appears to be more difficult to remove by bad guys than some that I have used." Read more

    115 customers mention71 positive44 negative

    Customers are mixed about the quality of the auto accessory. Some mention it's a nice quality lock, easy to use, and secure, while others say that it'll seek a refund on the unreliable locking mechanism.

    "...It’s so much better than the padlock I was using. Low profile and handy." Read more

    "...it still works but it alittle harder to turn and the key gets stuck. Although that is my fault and not the lock. I've decided to purchase a new one...." Read more

    "Works great! Screws down for a secure lock" Read more

    "Quality product and simple to use for keeping your trailer secure...." Read more

    26 customers mention18 positive8 negative

    Customers are mixed about the fit of the coupler lock. Some mention that it fits tightly around the couple, is super small, and works well. Others say that it doesn't fit their trailer, is tight with no give, and is not wide enough.

    "...It fits tightly around the coupler." Read more

    "...This one fits perfectly on the trailer coupler and looks nice. A lightweight popup trailer can be moved by hand so it’s vulnerable to theft...." Read more

    "...doesnt fit my trailer but the product is OK. it was my fault to order this one...." Read more

    "...Lock fits and works. Once the key unlocks the lock you have to unscrew the pin to remove the lock from the trailer. The lock has a nice finish...." Read more

    3 customers mention0 positive3 negative

    Customers find the auto accessory annoying, irritating, and awkward to use. They also say it makes for an awkward and semi tedious chore.

    "...When your key is attached to your keychain it makes for an awkward and semi tedious chore. Very annoying especially when you’re in a hurry...." Read more

    "Works well, little annoying..." Read more

    "Irritating to use..." Read more

    Wondering you get the hang of it uour good.
    4 Stars
    Wondering you get the hang of it uour good.
    Good for your trailer!!
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    Top reviews from the United States

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    Top reviews from other countries

    Translate all reviews to English
    Souxinh
    5.0 out of 5 stars Good quality
    Reviewed in Canada on May 14, 2023
    Adrian Abreu Vazquez
    5.0 out of 5 stars Muy bien
    Reviewed in Mexico on December 25, 2021
    hugo
    5.0 out of 5 stars SO FAR, SO GOOD
    Reviewed in Canada on March 20, 2024
    Shawn M.
    4.0 out of 5 stars Lock for seadoo trailer
    Reviewed in Canada on August 2, 2022
    Martin
    5.0 out of 5 stars Fonctionne bien
    Reviewed in Canada on November 1, 2022