"I bought this for a CYMA CM028u AK47 on the chance that it would fit, and it did. This rail will fit any CYMA AK which has a level straight block area where the stock attaches to the rear of the receiver. Take a look at the pictures of the AK's with a side folding stock to make sure.
Installation consists of drilling three holes, two into the receiver and one into the aforementioned rear block. Use a 1/8" drill bit for the receiver and a 5/32" bit for the block. The rail is spring loaded to allow for easy pull-and-flip up of the back portion, so measure carefully to allow for this action. Precise placement is very important, in order to maintain good alignment. Measure carefully and start your holes with an awl or pick, or use brad point bits.
Once installed, this rail looks very nice and allows for attachment of most scopes. Given the limitations of fitting rails on the top receiver of an AK, this attachment rail is as rock solid as it can be. To access the battery compartment, you pull back on the system to clear the rear retaining screw and flip it up out of the way (remember to first flip up the AK's rear sight to avoid damaging either part).
While the rails will fit any Picatinny device in terms of width, the spacing between rail segments do not appear to be standard (or at least doesn't match any of the rails I have). What this means is that if you have a device which is secured by two or more pins inserted into the space between the segments, it's going to be hit-or-miss that they'll line up.
Overall, I highly recommend this attachment. It adds functionality to any compatible AK, and at $10.95 it's about half the cost anywhere else."