CPR Aquatic BHCPR007TSx4 3/4" Thread x Slip ABS Bulkheads (Set of 4) Pack of 4 complete units 3/4" (0.75") High Quality ABS Bulkhead with a silicone washer and dome top for better structural integrity Thread x Slip (flange x stem) Fits standard schedule 40 or 80 PVC pipe & fittings; Nominal Pipe Size and Standard Pipe Thread apply to inside; outside threads are not standard PT Look for the CPR UPC label. Don't accept imitations