The SADLAK Front Rail Mounting System is designed for clamp-on type bi-pods and accessories with a QD Post to attach Harris bi-pods while retaining your stock sling swivel. The Steel Model uses a unique internal Oval Nut plates specifically designed to fit the contour of four popular M14/M1A stocks. Once the nut plate is installed the rail can be installed or removed without rifle disassembly using two external screws through counter bored holes in the rail. Notes: Choose your Front Rail based upon your stock style, i.e. Universal, Wood, Fiberglass, Synthetic or Supermatch.FOR NATIONAL MATCH STOCK CHOOSE SUPERMATCH.