cool, order a couple from eBay with free shipping. I think I bought the 1/4" though. I learn a cool trick recently to slip small hoses over an oversized barb. Heat the hose in boiling/hot water. It'll slip right through and when cooled, it's an extremely tight seal.I have been using these check valves, https://www.usplastic.com/catalog/item.aspx?itemid=23369&catid=489 in my CO2 system for about 3 years, with no failures yet. I have had, one in my tank, in the water, with CO2 going through it for all of that time, and it still works fine. They are made of plastics that are highly chemical resistant. Shipping costs for buying them drive up the cost substantially, but I still like them. I mistakenly bought the 3/16 inch size the last time, so it can be difficult to slip tubing over them, but they still work. The 1/8 inch size works much better.