Features Include: VRS 7" Drop-In Versa Base, Customize the VRS DI for specific applications, Mix full length & short rails with bumpers, Add more rails as additional accessories are needed, Fast configuration changes, Mil. Std. 1913 Picatinny rail dimensions, Fits all M4/AR15/M16 variants, Mil. Spec. Type III anodized 6061 T6 aluminum construction and Combat durable.