Happy HHTRB50H Hot Tub Filter - Fits Pleatco PRB50-IN. Happy - HHTRB50H. Pleatco - PRB50 IN. Unicel - C 4950. These Filters are compatible with the following hot tubs Why Happy Hot Tubs?. Max-flow Core to maximise the flow through the core of the filter and improve hot tub performance.
eBay