Hayward ECX176865 5/16-Inch - 18 Retainer Nut Replacement for Select Hayward D.E. Filter Anchor Socket Retainer nut replacement Fits hayward pro-grid vertical d.e. filter and micro-clear, pro-grid vertical grid d.e. filter Also fits hayward perflex extended-cycle d.e. filter and anchor socket models i_pfppts, sp1392 Size 5/16-Inch-18 Weight 5.2-pound