CROSSTAC ASC SLING CONNECTOR CLAMP ON The Crosstac Ambi Sling Connector (ASC) is designed to keep AR-15 firearms close to the body. The low profile clamp-on design slides over commercial and mil-spec buffer tubes with no disassembly. Patented, single locking screw design for smooth lines. Ambidextrous attachment point. Allows you to perform strong / weak shoulder transitions and operate the safety selector without impediment.