150 X 200 Signature/Bullfrog Spas 25SQFT Nature 2 Microban® Replacement CartridSignature Bullfrog 25sqft Microban Filter Cartridge. Has a open top and the bottom has a coarse thread spigot. The open top is designed so you can purchase a cap that will hold a Nature 2 stick in the centre of the filter. Filter dimensions: Height 150mm(not including handle or spigot), Width 200mm, Spigot ID 50mm. These filters are made with Microban antimicrobial protection technology. Box QTY: 4