The Daniel Defense RIS III Rail Interface System takes the proven design of Daniel Defense's two-piece RIS II rails-used by U.S. Special Operations Command (SOCOM) since 2006-and reduces weight while adding versatility by utilizing M-LOK attachment. You get the same proven free-float barrel design, durable aircraft-grade aluminum construction, and an uninterrupted upper rail platform with Mil-Spec 1913 rail of the RIS II. But you also get multiple M-LOK attachment points along the handguard, plus integral QD swivel attachment points on both side. RSR - CSFL-40AT