Popular replacement bulb for pond UVC units and filters which fits the following filtration systems: Filters Blagdon Midipond 20000 Evolution Aqua EazyPod Automatic Complete Evolution Aqua Eazypod Complete Green Evolution Aqua Eazypod Grey Complete Hozelock Bioforce Revolution 6000 Laguna Pressure Flo 10000* Oase Bitron 18 Oase Filtoclear 12000 PondXpert EasyFilter 20000 PondXpert Filtobox 12000 PondXpert SpinClean 20000 (pre-2019 version) Velda Clear Control 50 UVCs Blagdon Pro PondXpert Greenstop 15000 * If your model was made pre-2015 you need an official Laguna 20w bulb, however a regular 18w bulb is sufficient with any models made 2015 onwards.