The Wilkins 420 is a pressure vacuum breaker (PVB). It was available in 1/2″-1″ sizes and was produced from 1989-2014. The body is made of bronze. The original version of the 420 had male threads on the body and female threads on the bonnet. The only bonnet that is currently available is the new style with female threads on the body and male threads on the bonnet. A lead free version was introduced in 2010.