2 Pcs Black Plastic Dual Head Bike Bicycle Pump Head Nozzle Hose Adapter Connector

I ordered a pair of these pump head chucks and tested them upon delivery. First, the screw-on outside clamp is a very tight fit for many standard floor pump hoses. I measured it at 0.34″ I.D., and my hose at 0.35″, so I figured it might be somewhat snug, but it was indeed a very tight fit.But that’s not the big problem. After some effort, I managed to install one of the chucks on a floor pump hose. Worked fine on both Schrader and Presta valves. Yay. But I figured I’d better check the other one in the pack just in case. I installed the other one on the hose and tested it, and it worked fine on Schrader valves, but it leaked badly on Presta valves, making it unusable. Not good.Logged back into Amazon and requested a refund. Amazon instead suggested a replacement set, and I said ‘why not’. In less than 48 hours, the replacement pair was delivered. Good.And so I tested the second replacement pair… and guess what? One worked fine, and the other leaked badly in Presta mode. Seems to be a pattern here…And so the two bad ones are soon on their way back to Amazon, and the two good ones are in service on floor pumps. So at the end of this, I have the working pair I expected and paid for. But there was some unexpected effort, including the installation, testing time, and dropping off the return.