SKS Rear Cover with Rail

My Chinese SKS has a rail on the rear cover. Anyone know if any of these rifles left China with these things on them, or did someone add it.

I've seen ads for them on various places, but this one doesn't resemble what I've seen. It looks close to a standard cover.

Chris-bob said:

Favorite part is when people put an optic on the rail on the rear cover and try to sight it in...

Click to expand...

Thought about doing it when I bought it. Then I took it out to the range and realized this device is the definition of "rip off".

Anybody want it? Need to trade it for an original one. Might be fun of you have a scope with REALLY B I G cross hairs.