These are a brass ball valve, 1/4 NPT on one end and 1/4 hose barb on the other end. These will ship for free in the US $2.50. While they last. http://www.kegglebrewing.com/14-NPT-x-14-hose-barb-brass-valve_p_210.html
curious, do these have a check valve built in?
If you use the link, there are others that state "check valve" and cost more, so I doubt this one has a check valve.
"I am a homebrewer, and I approve this homebrew!"Alamo Stew's Homebrews
That is right. There is no check valve in these