The 3/4" Ames 4000B began production in 1997 when the Watts Regulator Company purchased the Ames company. Ames began to market the Watts 009 series as their model 4000B. There are minor exterior differences between the Watts and Ames, but internal parts are the same. The 4000B is a single cover, bronze body device. Modular design check assemblies with replaceable seats. A 4000B-M3 model was introduced in the early 2000s. Repair parts are different for the M3 model. No special tools are required for servicing.