NICREW Glass Submersible Aquarium Heater, Shatterproof Fish Tank Adjustable Water Heater, 50-Watt;

Adjustable Temperature
This sleek and compact heater is designed to work underwater and has a temperature range of 68 to 94 degrees Fahrenheit, so you can have the temperature flexibility you need for your unique aquatic environments, fish, plants, and invertebrates.

Shatterproof Design
Since it's waterproof and shatterproof, it's safe for daily use and won't harm your tank.

Easy to Use
Installing it is easy thanks to the heavy duty suction cups that can be attached to any side of your tank. Plus, it doesn't need any complex assembly so you can start using it out of the box.

Guard Protector with Suncton Cups
Perfect for ensuing that your fish are protected from touching the heater and getting burnt. Also protects against accidental damage to the heater itself.

Notices:
1. Before powering, make sure the heater is completely submerged in the water.
2. Before removing the heater out from the water, make sure the heater is unplugged to avoid dry heating.
3. The aquarium heater will stop working if the water temperature is over the one you set.
4. Please do NOT put the aquarium heater into the sand as this will cause INACCURATE heating.
5. Many factors may cause the differences, difference between measurement and actual temperature within the range of ±5 ℉.

Tips:
The best location to place a heater is near the water flow, such as the outlet (or inlet) from the filter, or in the stream of a power head. Because having water flowing directly past the heater more quickly and evenly disperses heated water throughout the tank.