Our UL-NW-2 lug is slotted for a tiny key. The slot measures only about .250" x .087". Enlarge this slot with a file, as necessary. Ideal for use with our 3/32" pin, the long slot allows the barrel expansion when hot. Milled steel, the flat base is about .500" wide, and the dovetail is .600" long. Use it on fullstock rifles.