The Spike's Tactical BAR2 rail system is a lightweight 1-piece free-floating quad rail. The main benefit of the BAR rail is to those who wish to have a suppressor inside of the rail or for those shooters who have large bear paw hands and who feel that skinnier rails are just too small (the BAR is about the same circumference as a DD rail with the popular Magpul XTM covers). It features five (5) QD Sockets, machined from 7075-T6 Aluminum with Type III Anodized Hardcoat Finish, scalloped rails for operator comfort, Anti-rotation system, barrel nut and shims, and welded mounting system. It comes with three (3) black Ergo rail covers, barrel nut with shims, heavy-duty QD sling loop, tube of Blue Loctite, and installation wrenches. This model is 7" in length, the inside dimension is 1.8", the outside dimension Picatinny to Picatinny is 2.42".