Review on 🦀 Zoo Med 4-Watt Hermit Crab Heater: Efficient Heating for Optimal Habitat, 7.3 x 4.2 x 1.8 inches, Lightweight and Compact at 5.6 ounces by Jimmy Hargrove

If your reservoir is well below the required limit or is very large, this probably isn't the ideal product for you. My 5.5 gallons stays around 70F though, so it's a nice warm place for my hermits to sit or sleep if they want to warm up a bit. One of them has a toasted bed buried next to him (it's taped to the back outside wall) and the other doesn't seem to care what his temp is, so I think it's a win-win! Didn't measure right next to it, but I'd say it warms the spot to around 74-75 F.