The Boston Valve’s one-way middle partition is excellent. I use 1/2″ ID x 5/8″ OD tubing with a couple -three layers of duck tape around it to get a seal inside the middle valve. (7/8″ is for the larger opening when using my inflation bag.) I don’t want to snag the longer top-up tube attached to a top-up valve and have it pop apart. Especially if paddling in whitewater and attempting to assist someone who is swimming with their hard-shell kayal. If they grab the tubing instead of the webbing I have for them to grab onto?
Oops! I could join them in the swim!
Bruce,
Fairbanks