The Wilkins 420 is a pressure vacuum breaker (PVB). It is available in ½” – 1” sizes and production began in 1998. The 420 was discontinued in 2014. The body is made of bronze. The original version of the 420 had male threads on the body and a female threaded bonnet. The current version has female threads on the body and a male threaded bonnet. A lead free version was introduced in 2010 (420XL).