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. Category: Aquarium Supplies/Maintenance. Sub Category: Heaters. Cubes: 0.0013. Weight: 0.6500. 8/100 watt heater for 20 gallon fresh and salt water aquariums. Fully submersible can be placed horizontally or vertically in tank. Automatically sets and maintains desired temperature. Visible temperature setting scale and accurate to 1 degree. Heavy duty shock-resistant glass safer for large fish. Top-quality heating element with superior insulation and heat distribution. Lifetime guarantee! 2 top quality suction cups included. Factory preset at 76 degrees F just plug in!