I bought this stick to slot into the bottom of my iMac. I only had 1gb to start off with, and after a year of installing what can only be described as 'rubbish' on my mac I decided to upgrade the memory. Now with this chip I have 3gb! Hard to believe (2+1) but its true. Now she runs real fast, reccomend to any iMaccer who doesnt want to amy excessive amounts for memory from Apple.