You will need an aquarium heater to keep your tank in a steady and controlled temperature, as proper temperature range is very important to fish and other Aquatic in winter. Our aquarium heater help your fish and other aquatic keeping away from stress and diseases by providing proper temperature. Features 1, The aquarium heater is operating as a staged heating, once achieved the setting temperature, it will stop heating for a while, and then continue working to maintain the temperature. 2, Easy to set and adjust to the setting temperature with the use of the temperature adjustment knob, offers simple installation. 3,Strong suction cup TIGHTLY FIX the heater to the tank. 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, Please NOT put the aquarium heater into the sand as this will cause INACCURATE heating. Size: A - 25W-3.5CM,A -50W-3.5CM,A -75W-3.5CM B-50W-24CM,B-100W-24CM,B-200W-26.5CM,B-300W-31CM,B-500W-31CM Package contains ·1 x heater with 2 x suckers Precautions: Delivery Time 15-20 days.Please contact us if you cannot receive the order after 30 days. If you have any questions, you can get in touch with us by email, we will give you a satisfactory answer within 24 hours; We have a variety of styles of Aquarium Heater. If you have time, welcome to our shop to buy, we will do our best to serve you.