Mazama MagmaFlow Replacement Bite Valve with One-Handed Push Button Shut-Off and Magnetic Retainer Upgrade your hydration pack, magnetic anchor keeps your bite valve tethered to shoulder strap until needed Fits popular brand drink tubes with 0.25 inch inner diameter Low profile push button shut-off prevents your bite valve from leaking during transport High flow, no-leak bite valve, activate the bite valve from any orientation Great for mountain biking