Help condition your spa water with the Natural Mineral Cartridge. Acts as a mineral spa water cleaner. May reduce the need for harsh traditional chemicals.* Compatible with all ozone systems. Designed to fit in the convenient center chamber of the Bullfrog Spas filter core cage (standard in 2018 and later spas or with Filter Cage Assembly (part #10-00417) in Bullfrog Spas manufactured from 2013 – 2017. It lasts up to 3 months.