Don't be fooled by Illegal inferior Chinese imitatation knock offs. Trip Alarm Co. is a U.S company holding a U.S patent on this design. Brand new "Quad" patented design Unlike our competitors, our "Quad" design allows for 4 separate trip lines at once allowing for 360 degree coverage unlike anything else on the market. You are also able to fully disassemble this alarm for cleaning and see the stunning craftsmanship and quality. No other trip alarm comes close for the money. ***New design features an adjustable firing pin depth and our most sensitive trigger mechanism yet! This unit is for alarm purposes only! Live shells CANNOT be used in this alarm, only blanks to alert of intruders. We pride ourselves on having the best quality tried and true perimeter alarms on the market. We were also one of the first manufactures of the 12Ga perimeter alarms going on 16 years now in the makings! Many of the competitors alarms use springs or other components that will rust. We GUARANTEE our 12 gauge alarms will never rust. Every working component is either stainless steel or brass and the body is solid 6061 aluminum. This 12 gauge trip alarm is made to last with a high quality aircraft grade aluminum body with brass and stainless steel internal mechanism. Works great for perimeter defense of your home, office, farm, barn, campsite and more. Also works great for fun in games such as paintball! The alarm uses a 12 gauge blank (not included)