There's a few different manufactures out there. Most in tank heaters have the same design and specs so I wouldn't go too crazy.
I use a 200W aqueon submersible for my tank and it works great!
Hope this helps!
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.