The Viking Tactics L.U.S.A. allows the shooter to select from four different attaching options. With the VTAC - LUSA you can use a quick detach sling swivel, a conventional sling swivel, a hook, or simply run the sling through the sling loop. The VTAC-LUSA. allows a wide variety of options without changing hardware. For armorers the VTAC-LUSA eliminates the need to stock four different sling attachment brackets. For shooters that use the quick detach sling swivel, the VTAC-LUSA is designed to lock in the swivel and limit rotation to 45 degrees.