"I bought this heater on a suggestion from a friend and it's by far one of my most favorite aquarium purchases. I had a 1 gallon filtered tank for my betta but once the cold months came his tank water wasn't staying in the 70's so I needed a heater suitable for a small tank.
This one suction cups to the side or back of the tank and is very low profile. Since I started using it my betta's tank is always between 74-78 degrees, just perfect for my betta!"