Check the listing for details. Vacuum Control Valve-Check Valve 5mm, Both Sides, Plastic, NOS, M6. Condition: New. Listed at 12.00 USD. Vacuum Control Valve-Check Valve 5mm, Both Sides, Plastic, NOS, M6 These are new old stock but were bulk purchased, so they are just loose in a big bag. No retail packaging. They are similar in size to some Ford branded 3 ways i also have listed. I can stretch Gates branded vac tubing sized 7/64 (2.8) mm over the fitting and barb. It is really tight. 5/32 vacuum hose fits tightly,7/64 ID FUEL hose will not stretch over it. (the clear pink stuff)1/8 ID FUEL hose WILL stretch over it ( more of the clear pink stuff)7/32 ID Vacuum hose fits easily and may leak without a clamp5/32 (4mm) Goodyear washer / radiator drain hose fits snugly These are what I have on hand that I can test easily. These are actually pretty rugged and stood up to many hoses being jammed on and yanked back off without breaking. I am sure they will become somewhat brittle with age and heat. I have a bag of these from some surplus auction. No idea what specific application they were for, hopefully some will work for what you need.