64500D: 3" in-line pressure control valve with victaulic adapter on inlet.
64500E: 3" in-line pressure control valve with victaulic adapter on inlet and outlet.
64510D: 4" in-line pressure control valve with victaulic adapter on inlet.
64510E: 4" in-line pressure control valve with victaulic adapter on inlet and outlet.
NOTE: It is not recommended to use option E on a valve without additional support to keep it from tunring in the piping.