AK Universal Receiver Blocks for all common stamped receiver AK's. Such as Chinese Type 56 and MAK 90, Romanian SAR, Hungarian, Russian/ Siaga, Egyptian Maadi. Length extends 1.535" 'from the back edge of receiver' (F.B.E.R.) AKRBU is drilled and tapped in two places to allow the stock to be mounted higher for use with optical sights. Includes a 1 1/4" sling mount which can be mounted on the left or right of the rifle. Weight 180g ( 6.42 oz) Using this Adapter with the 'Pig-Nose' adapter, you can mount a CAR-15 style stock to your AK. *** What is the difference between milled & stamped receivers? *** There are two major differences between a milled receiver and a stamped receiver. A milled receiver is machined out of one solid piece of metal, making it heavier than the stamped yet more accurate. The stamped receiver is made out of several sheets of metal that have been riveted together. While a stamped is lighter it is also less accurate than the milled receiver.