The Wilkins 420 PVB is a pressure vacuum breaker assembly. Production of the Wilkins 420 pressure vacuum breaker began in 1998. The body of the Wilkins 420 PVB is bronze. The test cocks are mounted on the ball valves. The air inlet float utilizes a rubber fold not a spring to generate the air inlet loading. The float of the Wilkins 420 pressure vacuum breaker also has a relief valve to protect against damage from freezing. The check of the Wilkins 420 pvb is a modular design with a contained spring and replaceable check seat.