When biking on rocky terrain and all day riding on the trails, keep a spare bike tube in case of flats with the Nishiki(R) Presta Valve 29'' 2.125-2.25 Bike Tube. This bike tube fits your 29'er mountain bike and is equipped with a Presta valve that is 33mm in length. It fits tires that are 2.125-2.25 wide and will get you back on the trails in not time. FEATURES: Replacement bike tube Best for mountain bikes Fits 29" tires with a width range of 2.125-2.25 Valve type: Presta Valve length: 33mm Tube width: 50mm Tube thickness: .95mm