Pentair/Rainbow R172514 Cartridge Filter, Pentair Rainbow RTL-50, Top Load,1-1/2"fptCalifornia Residents WARNING: Cancer and Reproductive Harm P65Warnings.ca.gov Rainbow/Pentair RTL-50, model R172514 is a 1-1/2"fpt top load filter. For use on portable spas, it is designed to mount in a niche so that the main body is under the shell of the spa, while the top is accessed from above the spa. This complete filter includes a niche lock ring (secures the body to the niche), lid lock ring (secures the lid), push down lever (to secure and release the lid lock ring), 50 sq. ft. cartridge, and lid w/o chemical feeder. (Lid w/ chemical feeder is optional)