Review on Alloy Bicycle Tube Presta Valve Extenders (2 Pack) 20mm-60mm for MBP Bikes by Fredo Zhan

I was really worried when I read half the negative reviews on here but when I got the valves a lot of people just weren't sure how to install them. You will need to remove and replace the valve core by sliding it onto the narrow end of the rubber gasketed extension. Then you put the valve core back on the tip and hey presto, done. If they don't seem to be working properly at first glance, you may not be doing it right. Haven't had them long enough to see if they hold air well but first impressions were good.