The 3/8" Wilkins Model 420XL pressure vacuum breaker began production in 2010 and is still currently produced. The 460XL is a lead free backflow preventer. The 460XL replaced with the 460, which is the non lead free version. The 460XL was designed as a spill resistant vacuum breaker. The check assembly is self contained and has a replacable seat. Leaded and lead free versions use the same internal parts. The bonnet has a built in tool to disassemble the check assembly.