OUTDOOR WEATHERPROOF - designed to be weather-proof, so they are able to be installed in most locations around the garden, or in a shed or garage, close to your chosen power supply COMPLETE KIT - includes 2 air hose lines and 2 air stones INCREASES OXYGEN IN THE POND - fish and other pond life require oxygen-rich water in order to remain healthy. Filter bacteria, essential to the breakdown of highly toxic ammonia and nitrite, also require oxygen to flourish and keep the pond free form the build up of toxic waste HELPS PREVENT POND STAGNATION - the use of a Blagdon Pond Oxygenator will increase the level of oxygen in the pond and reduce levels of carbon dioxide, thus aiding in preventing the pond from stagnating by injecting air into the water HELPS PREVENT SURFACE FREEZING - in winter, use of an air pump will keep an area of the pond ice-free, preventing the build up of toxic gases which can be fatal to fish and other aquatic life