The 1/2" Watts Series SS009 Reduced Pressure Zone Assemblies are a stainless steel RPZ device. They began production in 1992 and still are being manufactured. The SS009 features a one cover design and use check modules that slide into the body and are held in place with a retainer. The relief valve assembly slides down between the retainer and is directly under the cover. The check modules and relief valve assembly come apart for service. No special tools are required for servicing SS009 Series devices.