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If you have the mid-2012 MBP, that's the non-Retina model, which does not require the Pentalobe screwdriver you link to. It just needs a Phillips #00 screwdriver. I have that model and that's all it required to open it up. If you have the late-2012 Retina model, that's the one which requires the Pentalobe screwdriver. (The 15" 2012 Retina MBP was a mid-2012 model.) The iFixit site just says "P5 Pentalobe Screwdriver" for the MBP and MBA so I can't say for certain that that's the one (probably is).
 
The Phillips #00 is what you need to open the mid-2012. The listing doesn't go to 2012 probably because it doesn't work for the late-2012, but it will work for the mid-2012. Make sure you have the right model - the mid-2012 will say Model A1278 on the bottom of the case.

Once the case is open, there may be additional tools needed depending on what you want to do. For RAM, no other tools are necessary but changing the RAM is slightly more difficult than many other computers because the bottom slot is not offset from the top slot. If you're doing a HDD replacement, you need a Torx T6 screwdriver. Changing the battery also requires additional hardware. The iFixit site has a good set of instructions for most of the typical operations. Note: Both the Torx T6 and Phillips #00 screwdrivers can be found at many hardware stores - this is likely not the case with the Pentalobe screwdriver.

https://www.ifixit.com/Device/MacBook_Pro_13"_Unibody_Mid_2012
 
The Phillips #00 is what you need to open the mid-2012. The listing doesn't go to 2012 probably because it doesn't work for the late-2012, but it will work for the mid-2012. Make sure you have the right model - the mid-2012 will say Model A1278 on the bottom of the case.

Once the case is open, there may be additional tools needed depending on what you want to do. For RAM, no other tools are necessary but changing the RAM is slightly more difficult than many other computers because the bottom slot is not offset from the top slot. If you're doing a HDD replacement, you need a Torx T6 screwdriver. Changing the battery also requires additional hardware. The iFixit site has a good set of instructions for most of the typical operations. Note: Both the Torx T6 and Phillips #00 screwdrivers can be found at many hardware stores - this is likely not the case with the Pentalobe screwdriver.

https://www.ifixit.com/Device/MacBook_Pro_13"_Unibody_Mid_2012
[doublepost=1460077035][/doublepost]OK thanks for the info, just wanted to try an SSD in it
 
As I said, replacing the HDD requires a Torx T6 screwdriver. The spudger mentioned at the iFixit site is also useful. Sometimes, people have problems with the cable - it will work for the HDD but not a SSD. Those issues are more common with the older 2012 models (they still manufacture this model). Try it out before spending the money for a new cable. If you want to -add- the SSD (taking out the optical drive), it's a bit different - you need a bracket.
 
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