where to get small check valve

[h2o]

i want to get check valves for plumbing of my tank. was at HD, grainger..but neither don't have a barbed check valve the size of 1/8-3/8"
Internet do sell co2 check valve, but i am still searching ones for water travel check valve, can someone recommend a place?

 

[david s]

I got one at a local plumbing supply but i found when u put the barb fitting in hose it restricts it some if i used another check I would go larger check and try to reduce it and find somthing so i didnt restrict flow with a barb fitting