Fluval M100 Submersible Heater 100 W, up to 30 US Gal / 100 L

A mid-size submersible heater for tanks up to 30 US gallons, sitting between the compact M50 and the larger M-series units. Fully submersible with a simple mechanical dial, it's a straightforward, no-frills option for standard community tanks that need reliable heating without the added cost of electronic temperature readout.