If you have a 2012 or 2013 model 27" iMac then you can use this to upgrade the RAM in your iMac to 12Gb. iMacs usually shipped with 8Gb of ram, this is a really cheap and easy way to get a performance increase. The best thing is that you can do it yourself because it is so easy. If your iMac has the razor thin edge then this is the RAM for you

4.0GB(2.0GB+2.0GB Kit) PC12800 DDR3 1600MHz SO-DIMM Memory

This RAM will fit only the 27" iMAC, the 21.5" iMac is considered to have non user upgradable RAM and is very difficult to upgrade

If you want to check what RAM you are using, just click the Apple logo in the top left hand corner of the screen and click "About this Mac"

The window will tell you what memory you have and it should be 4Gb 1600 MHZ DDR3. When shipped the iMacs have two empty memory slots and that is where you install this RAM. It is as simple as undoing some screws, pushing in the RAM and doing the screws back up

You can check you model and RAM type here is you like:

http://www.everymac.com/ultimate-mac-lookup/

and put in the last three digits of the serial number of your iMac. (If you still have "About This Mac" open, you can click twice on the word Version under the MAC OS X and you will get your serial number)

You do need to have 4Gb and the 2 free slots available for this RAM upgrade. If you want to see whats involved you can check on YouTube or iFixit but it is easy to do

This will work with the very new iMacs with the razor thin 5mm edge

Why buy from me? First of all check out my feedback (and please actually read some) - if that's not enough, be secure in the knowledge that when you make your purchase, your first email from me will contain my REAL name, address and phone number - I don't hide behind some hotmail address! (member no. 3443 - I joined trade me as one of the first in 1999 and haven't put a foot wrong since!)

Installation is super easy!!! But I'll happily install it for free for you if you prefer

The photo is a generic one and not the actual RAM