Even without a battery-powered motor whirring away inside, Nerf's mechanical blasters aren't exactly silent when being reloaded and fired. So for those times when stealth is of the utmost importance, the Nerf Zombie Strike Silent Strike is a simple lung-powered blowgun that won't give away your position.
Using it is as easy as loading a dart in the tube, taking a big breath, aiming, and then blasting your target with all the force your lungs can muster. A special valve in the mouthpiece ensures you won't accidentally inhale a loaded dart, and the range is claimed to be as far as 17m. But if you're not against causing serious internal bodily harm, you can probably get even more range with a stronger blast.