Still keeping great pressure havent loss any psi. diffent design along with the brass. My unloader has a by-pass.
Not sure what they are made of. They are the same color as the old ones. If that helps
Just out of curiosoty, why are you having to rebuild pums. Did you run them with out water? I have some that have over 4000 hours. I have yet to have to rebuild a pump or replace packings.