Pentair R172374 Lock Spring Replacement Top Load In-Line Pool and Spa Cartridge Filter Lock spring replacement Fits Pentair high capacity automatic feeders models HC-3315, HC-3330, HC-3340 and Dynamic Series V DSC 75 and DSC 100 Also fits Pentair Dynamic Series II and III RTL/RCF pool and spa cartridge filter Measures 1-16/25-inch length by 9/25-inch height by 6/25-inch width