On the page You can find prices for: mini submersible heater
Marina C10 Compact Heater, 10-Watt
$11.86
FREESEA Small Aquarium Betta Submersible Heater with LED Temperature Display (50-300Watt)
$23.80
Aqueon Fish Tank Mini Heater, 10-watt, Plastic
$9.69
Aqueon Mini Heater, 10W
$12.54
Marina Submersible Heater for Aquarium, Mini, 25-watt
$14.99
Aqueon Preset Aquarium Heater, 50W
$9.84
JunBo Mini Aquarium Heater Submersible Heater for Small & Mini Fish Tank Under 10 Gallon, Intelligent Constant Temperature, Overheat Protection System, 25 Watt (US Standard Plug)