Perfectly compatible with my iMac 2009 model, the replacement is done in 3 minutes, with 8 gigabytes my iMac found a second youth, because the system has not to constantly appeal to the hard drive towers 5400, applications more memory, and the system is much more responsive. In short need to change my iMac to buy a new one. With the mavericks update that adds more memory compression everything is perfect. Fast shipping, received in 3 days very solid package.