The Streetwise stun gun is a self defense device which disrupts the message the brain sends to the voluntary muscles. Simply touching an attacker with a stun gun for three to five seconds will deliver a shock causing loss of balance and muscle control, confusion, and disorientation bringing him to his knees and making him incapable of further aggressive activity. Full recovery takes about five to ten minutes and there is no permanent harm. Requires one 9 volt battery (not included). Streetwise brand stun guns have more features than any other stun gun on the market. Built-in 130 dB alarm: this stun gun offers you to levels of protection. At the first sign of danger you can activate an ear piercing alarm to scare off a potential attacker and summon help. If the alarm sound is not enough to deter the attacker, the stun gun may be used. Disable pin: prevents an attacker from taking this stun gun away and using it on you. A strap worn around your wrist attaches to a disable pin on the bottom of the unit. If this stun gun is taken away from you the disable pin will pull out, preventing it from working. The disable pin adds an additional safety feature for parents; removing the disable pin prevents a child from accidentally turning the stun gun on if they happen to find the unit. Safety Switch: to prevent accidental discharge, three levels of safety have been built in. The disable pin must be inserted, the safety switch must be in the "on" position, and the trigger pressed down before the stun gun will operate. Holster Included: although it is small enough to carry in your pocket, it can be clipped to your belt or purse, or carried in the included holster with belt loop. Life time Warranty: Streetwise Stun Guns are one of the highest quality brands available and come with a life time warranty. Requires one 9-volt battery ( not included).  The stun gun dimensions are 4 and nine-sixteenths inches x 2 inches x 1 and one-sixteenths inches.