Penn Plax is a name that stands for Quality Innovation and Integrity In the Pet Industry for over 50 years Experience a great line of Pet Products in all categories! Penn-Plax is committed to creating and manufacturing innovative pet products for first-time pet owners and serious hobbyists alike. Submersible heater for tanks up to 10 gallons. Category: Aquarium Supplies/Maintenance. Sub Category: Heaters. Cubes: 0.0013. Weight: 0.5500.