Both adapters worked well with all the pumps I've tried them with so far. I'm not sure what the longer Presta valve expansion adapter is for, but the two parts I care about are fully functional. I store the two adapters together in my bike pouch along with a patch kit for extra versatility on rides.Presta Tire Valve to Schrader Pump:Open the tire's presta valve fully, then carefully slip the copper adapter past the valve and onto the threads to not lose air before pumping. From there, get the adapter finger-tight so the valve can be pressed by the pump pin.This adapter doesn't leak air when attached, so it could be stored on the stem when not in use. However, I would recommend taking it off and closing the presta valve when it's not being used to prevent the presta valve from leaking since they can be a little touchy when open.Schrader Tire Valve to Presta Pump:This adapter slowly releases air while it's attached, so have your pump ready to go if you don't want to lose air before pumping. This also means it can't be left on the valve stem when not in use. Once the adapter is installed, you can put your finger over the presta hole to prevent air from seeping out before you attach the pump. Once the tire is inflated, remove the pump and put your finger over the hole while unscrewing the adapter to prevent unnecessary air loss.