Unused Aquarium Heater Key Features: ★ "Oops!"-Proof Safety Features 　　Heater with automatic temperature control ★ Automatic 18°C Heating 　　Maintains a water temperature of 18°C, which helps goldfish stay healthy and eat well. ★ For small aquariums up to approximately 21 liters. * The box has some damage, but the contents are fine. I'm selling this to someone who was looking to improve the environment for their cute pet.