I got a couple of rings from Bowman for an SF46. Super service, replied to my emails real quick. Rings were perfect, did not have do any gapping. I've only used 1 of the rings so far. He included a list of all the rings he has specs for, which was a very long list. And yes, if provided the piston and cylinder he can custom make them. I think it was $20 shipped for the 2. A very fair price for a quality product, in my book anyway.