Why Latex? Compared to standard bicycle inner tubes which are made of butyl rubber, Latex is significantly more elastic (10x elongation compared to 2-3x), but more importantly, Latex Rubber has significantly lower coefficient of damping which means that when latex rubber is stretched or flexed, it returns to shape faster and with fewer energy losses.What does this mean for an inner tube? Latex inner tubes are generally 2-5 Watts (per tire) more efficient at 30mph than tubes made of other materials, are harder to pinch-flat, and offer superior suppleness and road feel, especially when combined with supple, low rolling resistance tires.The Silca Latex Tube 700x24-30mm + 40mm extender and speed shieldhas been sized to fit tires measuring 24-30mm, which will equate to 23-28mm tires used on modern wider rims. Valve stem length is 42mm and will work in all modern disc wheels.Optimized for tires measuring: 24-30MM (Tires marked 22-28mm when used on wide rims, or tires marked 24-30mm used on older narrow rims)Premium Latex42mm valve stem, works in all modern disc wheelsRemovable Presta valve core85 gramsPlusFully Threaded 40mm Valve Extender and SpeedShield Rim protector - protect rims from valve nut damage, eliminate valve stem rattle and improve aerodynamics.Silca Latex Tube 700x24-30mm + 40mm extender and speed shield Pink Highlights:High precision CNC machined Aluminum Valve Extender with full external threadsIdeal valve extender for use on Carbon RimsCompatible with both Tubeless AND Standard RVC valve stemsLess than half the weight of brass valve extendersSpeedShield Improves wheel aerodynamics up to 0.5 Watts at 30mphSpherical nut eliminates bending forces on valve stem for improved strengthSilences Valve Rattle in Deep Carbon Rims while protecting carbon rim surfaces