Ames is a leader in the fire industry and is often requested by fire contractors for install and repair parts. Their website even indicates their focus is the fire industry: www.amesfirewater.com They specialize in stainless steel backflow assemblies today but some of their older models were epoxy coated. Each generation of assembly they come out with gets better as far as design and being able to replace rubber gaskets for example instead of the complete check assemblies.
Ames is now owned by Watts so you will find that each company will private label assemblies for the other resulting in some confusion among contractors when they see an assembly that they know as either Watts or Ames and see a different model number. Ames does have a YouTube channel that show you how to work on these new generations of assemblies. Their channel is: www.youtube.com/user/AMESbrand/videos
We stock a variety of the repair kits for these models. The assemblies we have ship direct from the manufacturer as they offer free shipping on their 2 ½" and larger ones and it could result in a shorter delivery time depending on the location it ships from.