Blem receivers have cosmetic or machining imperfections that are 100% functional. Imperfections includes dings, scratches, machine marks, or mismatched color tones. The Super Duty Receiver Set includes a Geissele Super Duty stripped lower and a Geissele Super Duty stripped Upper receiver. This high quality receiver set is precision machined from 7075-T6 and finished in durable Lunar Black, OD Green, or DDC Type 3 hardcoat anodize. With laser engraved T-marks and SAFE/FIRE markings. Please note the Geissele Super Duty Receiver Sets are not a "matched set". The shades of anodize between the upper and lower may be slightly different and they are Mfg: Geissele Automatics