hex socket plug 300# galvanized steel – 1/4” extra heavy class 300 specifications: ansi b1.20.1, threads. B16.3, dimensions, pressure rating. A.s.t.m. A 197, material. A153, galvanizing. pressure ratings: 300 p.s.i- saturated steam 1/4” – 1” – 2000 p.s.i – at 150 degrees w.o.g 1-1/4”-2” – 1500 p.s.i – at 150 degrees w.o.g 2-1/2” – 3” – 1000 p.s.i – at 150 degrees w.o.g (sold in quantity of 100 pcs.)