This is a replacement 18W - UV Lamp for the Hozelock Revolution 6000. These bulbs are standard so it will fit any 18w unit. UVC Bulbs should be changed at regular intervals, ideally in the spring before the season starts. This is to guarantee the full strength capacity of the UVC to tackle green water or any other algae problems. When changing a lamp make sure you use a glove or cloth to handle the bulb as touching the bulb with your hand can damage the lamp long term. These bulbs are of the PLS design, and have 2 small pin connections at one end only.