Features: 1.The Finest Filters new and improved external heaters are ideal for aquariums up to 500 litres in size. Our external heaters come in two sizes EH-300 for aquariums up to 300 litres, and EH-500 for aquariums up to 500 litres in size. The heaters have an LED indicator which lights up when the heater is operating. These heaters display the temperature in degrees celcius. 2.Please Note: This is NOT a submersible heater, and should under no circumstances be submerged in the aquarium. This heater can ONLY be connected to an external canister filter outlet pipe, so water is pumped through the heater from the external filter. 3.Both model of heater measure 310mm long x 90mm wide x 80mm deep. 4.These heaters come supplied with 3 sets of hosetails, so you can either connect to 12mm internal /14mm external hose,16mm internal / 22mm external diameter hose or 20mm internal / 24mm external diameter hose. 5.This heater is 220-240V and supplied. Specification: style300w/500wAmerican gauge plug size31x8cm/12.2x3.15inch weightabout 500g materialplastic colorblack Package 1xthermostat 3 xHose set