Instructions: Inserts between valve body and valve core, making inflation and deflation very easy. Make sure that you open up the existing valve on the tire all the way and that you do not close it again, when you screw on the extension. Sometimes using Lock-Tight can be helpful to achieve a perfect seal, if your existing valve is worn. Aero and deep dish aero rims require that you use a longer stem Presta valve. All Gray wheels come standard with valve extenders, but if you need more, here you go. Available in variety of lengths to specifically compliment GRAY Wheels. Available lengths rim compatibility: 35 mm for 5.0 and 45WLX, 45WLC wheelset / 70 mm for 9.5 and 80WLC wheelsets