Bobro Engineering B02-004-000 Aimpoint M4/M4S Must be Compatible with any 1913 specification rail, to include Systems that are out of specification (within reason) and this includes Weaver rails Must be completely tool and user adjustable free. It needs to be 100% self contained and mate securely to any rail without the user having to tailor the pressure/engagement position Must lock with enough pressure to positively attach any device or optical instrument to a rail without movement, Static or dynamic forces not withstanding The rail must not experience any deformation due to user error. This must include synthetic (plastic/polymer/composite) rail Systems Unit must not shoot loose due to improper mounting or a mechanical bottoming out