Our UL-NW-S3 is slotted for a standard large key. You may enlarge the .360" x .120" slot to accept our Key-36-I. Be sure to order the matching IN-Slot-2 inlays, which are pre-cut to exactly fit that key. The concave base measures about .500" wide x .740" long. Solder this lug to your round barrel, for use with a key.