Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: Hi! This kit fits on upper or lower disk bay?
Document: I purchased this kit over the OWC one due to the extra bits included with the screwdriver. I did have an issue with installation however. My 2012 Mac Mini had the stock hard drive in the to bay (closer to the aluminum from inside the casing) and the sata cable was the same as the one already in the case.
It has everything you need to mount an extra disk in your Mac Mini, if you have skills to deal with electronics, tiny plugs and so on. If not, I recommend that you give the Kit to a professional to have it installed.
Used this to add an ssd to my Mac mini so I could create a fusion drive.. Way cheaper than buying from apple.It's a little tricky to install but the kit supplied fits perfectly.
When right side up the connector for the bottom bay should be 076-1412. The connector for the top bay is 076-1413. I would suggest looking into the system information->serial ATA and clicking the hard drive to find out in which bay your HD is in to purchase the other sata cable.Here is a link I found with the part numbers for the sata cables for the different model years, I'm not sure if there is a difference or not [...]
This kit was great when I went to add a 2nd drive to my Late 2012 Mac Mini. The SATA cable came pre-bent to used in the upper tray. The tools look to be of decent quality, but getting the bits out of their slots are somewhat of a pain. Installation went smooth when following the iFixit instructions.
I had to straighten the SATA connector for it to fit.So far, it is working, I will check the logs again to see if I am getting any errors.Edit (03-29-14):I reloaded my Mac back to Mountain Lion, the SSD is no longer visible in the Disk Utility, so I am running on the installed 1 TB drive.
It was a challenge to make all work, but it worth it. I put dual SSD's, one for OSX and one for Windows using boot camp, so I didn't have to partition the OSX disk. For me, it's the best configuration I've ever thought for my brand new Mac mini 2012. The internal parts of the Mini are really fragile, so take your time to perform the steps of the guide.
perfect kit, every thing you need + a neat tool set when you are finished.
This kit worked for me. Watch Utube videos and read the online instructions and had no problems. I highly recommend it.
I chose this kit over the OWC's one as ifixit items has not let me down, thus far. Screwdrivers included are good, but not great.
Answer: With this kit I was able to install a 2nd hardrive in the lower drive bay kit. it's worth the price, on the ifixit site it was 70.00. Both drives are up and running and you should be able to do the install with instructions from ifixit. Good luck if you need more assistance contact me here on amazon