The Ames C500N and C500Z are reduced pressure detector assemblies (RPDA). They are available in 2 1/2″-10″ sizes and have been in production since 2000. Their bodies are made of stainless steel. The C500N is an “N” shaped device and the C500Z is a “Z” shaped device but they share the same parts. The C500N and C500Z have used multiple devices for the bypass assembly. Both currently utilizes a 3/4″ 919 for the bypass assembly. A lead free version (LFC500) was introduced in 2013. The Watts 957NRPDA and Watts 957ZRPDA are private labels of the C500N and C500Z.