Kustom Kraftmanship has a web site which can I believe be accessed from one of the links at the end of the stuntworks page Davis Model Products soes not have a site at this time
Kustom Kraftsmanship is www.kustumk-modelairplanes.com. The one way valve that fits into fuel line is # 515, not 555 as I thought. I use them in crankcase pressure lines and in caps for uniflow tubes.