This product is not 100% Macbook Pro Compatible. I have a MBP 13" early 2011. There were no instructions included (I used a guide at ifixit). To install this was quite tricky and required removing a piece of plastic from the hard drive enclosure (shown already detached in the product picture). Also the enclosure doesn't have the screw holes necessary to secure the enclosure to the inside of the MBP case.
Unlike the other reviewer mine run at SATA 3gbps, this was fine for the 5400rmp drive that I installed (I have an SSD in the main hard drive bay at SATA 6 gbps). I think that Apple (and others) may put the optical drives on slower SATA ports, so the bottleneck doesn't seem to be this enclosure.
I was able to get this installed and working first try, and there is no loose movement inside the case (despite the missing screws). It does the job well and for the price is a bargain.