KNS Precision Re-Enforcer for Lightning Link. Installation may require removing .040 material from the bottom of the upper receiver take-down pin lug and a small amount from the back of the hammer. Installation and use of this reinforcement does not imply or express any liability guarantee or warranty upon the manufacturer or seller to cover the cost or value of the firearm firearm accessories or lightning link in the event of accident loss or breakage of any kind. The Bureau of Alcohol Tobacco Firearms and Explosives has approved the use of this product on legally registered Lightning Links in accordance with the National Firearms Act (NFA). HOWEVER USING THIS REINFORCEMENT PIECE TO REPLACE ANY PART OF A REGISTERED BROKEN LIGHTNING LINK WOULD CONSTITUTE THE MANUFACTURE OF A NEW UNREGISTERED MACHINE GUN AND WOULD BE IN VIOLATION OF THE NFA. (Ruling #903050:MRC 3311/2005-474) Detailed instructions and helpful hints included. Specifications for KNS Precision Lightning Link Re-Enforcer: Manufacturer: KNS Precision Additional Features: Weight - 0.2 lbs Dimensions - 5 x 4 x .5 in Country of Origin: USA Package Contents: KNS Precision Lightning Link Re-Enforcer KNS Precision LLINKR: Re-Enforcer for Lightning Link