Bought two male foster fittings each, 1/8 NPT and 1/8 BSPP, just to have in my PCP supplies, as well as a 10-pack of Delrin Washers. Doing it all over I might have bought a pair of the 10mm fittings, too. In setting up my Yong Heng fill station I laid everything out as I wanted, then figured out what hoses and adapters I needed. Purchased hoses with the appropriate foster fittings already installed so when they arrived, I snapped the system together. Like you, I needed a double end male foster fitting (pictured earlier) to attach female foster fittings together in several locations. Bought a 3-pack off eBay for $9. WM