This is a Knight's Armament free float RAS MRE (Modular Receiver Extension), KAC part # 21166-2. This version has the front filler tube with rails. Condition is new-in-box, as shipped from Knight's with 3 11-rib panels.
Price is $275 shipped. I prefer PayPal, or a USPS money order. No trades at this time.
The MRE is sold. Thanks.