through the fingers, allowing the light to be used in a tight two handed grip on a handgun, with the switch controlled by pulling back with the fingers on the ring. More traditional models can be used as well. Some flashlights feature a momentary on switch so that the light is quickly turned off by releasing finger pressure on the button. Another useful feature is the ability to attach a lanyard to the light, allowing the light to be secured to the hand holding it; this allows the light to be dropped if the hand is needed (for a magazine change, for example) and quickly retrieved. Police often use large flashlights like the classic D cell Maglite, a sturdy metal unit which, when held correctly, can double as a billy club and as a tactical light. The flashlight is held in the weak hand, with the back of the flashlight extending past the thumb. This allows the light to quickly be reversed, swinging the back end of the light forward to strike the target or block a blow. The strong hand can then be used to draw a sidearm, and place the hands back to back to provide support and illumination in the firing position. Smaller tactical flashlights often have crown-like protrusions around the lens to enable its use as a weapon by hammerfist strike. Weapon-mounted lights Hand-held flashlights were introduced about 1900 with availability of dry cell batteries and incandescent light bulbs. Early bulbs were often too fragile to survive the acceleration of firearm recoil. A United States patent was issued in 1912 for a night sight for firearms demonstrated on a revolver with a bulb mounted in a shock absorber below the barrel and the grip modified to hold a battery and include a pressure switch. Weapon-mounted lights (sometimes called "weapon lights") offer hands-free use, leaving the operator free to use both hands to control the weapon. For rifles, two hands are needed to use the weapon. Most models have an on/off switch mounted on a short wire. The switch is then mounted somewhere on the gun within easy reach of the firer's fingers. Weapon-mounted lights are most commonly seen on rifles, shotguns, and submachine guns, but small tactical lights are becoming more common on handguns as well. These lights are often much more expensive than the handheld lights, since they must be sufficiently robust to withstand the