ME870S-6 3/4" FNPT x 3/4" MNPT Back Pressure check valve 
ME870S-10 1 1/4"" FNPT x 1 1/4" MNPT Back check valve - Steel
ME870S-12 1 1/2"" FNPT x 1 1/2"" MNPT Back Pressure check valve
ME870S-24  3" FNPT x 3" MNPT Back Pressure check valve Steel