2HoleShort Barrel Copper Compression Lug w/ PeepHole1000 MCM-1/2" Bolt Short Barrel Copper Compression Lugs with PeepHoleis a type of copper compression connector that is produced from high conductivity copper tubing. They are tin-plated to provide corrosion resistance and are marked with die index and color coded for easy reference. Listed for 35KV maximum when properly installed.