AIR-VENT VACUUM BREAKER ASSEMBLY FOR 420 & 450BFP FROST-PROOF HYDRANT SERIES 420LF USED ON MODEL/BRAND; ANTI-SIPHON FROST-PROOF WALL HYDRANT USED ON ITEM; AIR-VENT ASSEMBLY MROSCS LEAF CLASS NAME; INCLUDES GREEN CAP, PLASTIC BODY AND PLUNGER, O-RING AND PLUNGER SEAL