Open box item. See pics for actual product.

From the manufacturer:

Tetra HT Submersible Aquarium Heater With Electronic Thermostat

Tetra's HT line of heaters are easy-to-use and work in aquariums ranging from 2 to 55 gallons. The heaters have electronic thermostats that automatically adjust heat output to keep water at a constant 78 degrees F. All HT heaters have indicator lights to let you know when the heater is on, heating the aquarium.

All Tetra HT heaters have red/green indicator lights to let you know when the heater is heating(red) or on standby(green). The low voltage thermostat maintains water at 78°F without any adjustment required. Be sure purchase the correct heater for your tank size. Buying a heater too small for your tank can cause under heating. It is critical to ensure your tank is equipped with a hood or glass canopy to contain the heat inside the aquarium. All Tetra HT Heaters will shut off if an electrical short is detected for your safety.

Description

Tetra® HT Submersible Heater is designed to keep your aquatic fish comfortable, with an electronic thermostat that automatically maintains a consistent water temperature of 78 degrees and prevents overheating, extending heater life. An indicator light lets you know when the water is heating (red light) and when it reaches the proper temperature (green light). Inside, silicon carbide crystals improve heat distribution and transfer. The strong glass tube is heat and shock resistant. This submersible heater is easy to use – just attach to the inside of the aquarium wall using the suction cup (included) in an area with good water circulation. The Tetra HT Submersible Heater is available in different wattages to fit your aquarium: use the 50-watt HT10 in 2 to 10 gallon aquariums; 100-watt HT30 for 10 to 30 gallons; 150-watt HT40 for 30 to 40 gallons; and 200-watt HT55 for 40 to 55 gallons. This heater is UL Listed. Since 1951, Tetra has developed the world’s most comprehensive body of fish food knowledge, and fishkeeping enthusiasts have looked to the brand for products and solutions that add ease and beauty to their home. Whether you're an experienced hobbyist or just starting out, Tetra has everything you need – from a large variety of quality fish food and innovative equipment to test kits and decor.

Features & details

All Tetra HT heaters have indicator lights to let you know when the heater is on. It will be red when heating and green when the proper temperature has been reached.

The HT20 uses a built in electronic theromstat to automatically maintain water at 78° F which is ideal for most tropical fish. No adjustment is requried.

Ideal for aquariums between 10 to 30 gallons with hoods or glass canopies

The HT heater is fully submersbile and can be installed vertically or horizontally. Its small footprint makes it easy to conceal behind plants or other décor.

Please read all label information upon delivery. DO NOT plug heater into an electrical outlet until it is placed inside the aquarium.