The Street Defender is the top dog in the highly recommended ASP line. This one is a bit bigger and may be a bit much for a key chain. We like it. You will have thirty half second bursts or 15 seconds total effective out to 10 feet. As all the ASP products, it is great as a hand held impact weapon also. Hold it like a knife and strike the face around the eyes or temple to get full effect. It is a cone, not a stream, so aim is not as important. Aim at the face, spray and run. Remember, OC only gives you a pause in combat. Don't expect incapacitation. This will give you time to get away, or time to get to a more effective weapon. The most common effect of spray is temporary blindness lasting a few seconds to a few minutes. The safety devise on the ASP product is a small plastic clip that slides over out of the way with the thumb. This prevents accidental discharge. ASP products can be refilled for about 20% of the original cost. We highly recommend these items and demonstrate them in our classes.