Good company..I needed ceramic disc and made a phone call. Parts came in two days. 2 new valves came, although I asked for one. Keep the instruction book stored in a safe place.
I screwed up disc's during install. I don't think this valve will ever fail, very good design and quality.
I think I screwed up the original disc, because I didn't flush the solder balls from the water pipes thoroughly, A solder ball damaged the disc when it was lodged in the valve.