Warning!! Use correct .22 caliber blanks only! (Not included) Use with caution and follow instructions carefully!! These alarms have several uses. Primarily designed to use as a perimeter alarm for camp, these with let you know quickly if anyone or anything is entering your space. Use these as a deterrent for trespassers or unwanted critters, or as a way to slow down and disorient would-be enemies hot on your trail. The list of things you can do with these is a long one.