3/4" Single Union w/ O-ring Seal, PVC Schedule 40, F-NPT x F-NPT - 10pk 3/4" Single Union w/ O-ring Seal, PVC Schedule 40, F-NPT x F-NPT - 10pk Priced at only $1.26 each in this Special 10 PACK Offer! 3/4 inch Female NPT threaded connections. Hi-Impact PVC Type II Material. EPDM O-Rings. ASTM D2466, Schedule 40 size and material standards.