Some of the iMAC models have 3.5" drive bays. If you ahve one of those models you would need some mounting brakets as the SSD drives are 2.5".
All “Late 2009” iMac models – the iMac “Core 2 Duo” 3.06 21.5", “Core 2 Duo” 3.06 27", and “Core i5” 2.66 27" – and all “Mid-2010” models – the iMac “Core i3” 3.06 21.5", “Core i3” 3.2 21.5", “Core i3” 3.2 27" and “Core i5” 2.8 27" – have a 3 Gb/s SATA 2.0 connector for a 3.5" hard drive. The 27-Inch “Mid-2010” models – the iMac “Core i3” 3.2 27" and “Core i5” 2.8 27" – also have an extra 3 Gb/s SATA 2.0 connector and power for the optional 2.5" SSD (in addition to 3 Gb/s Serial ATA 2.0 connectors for the hard drive and optical drive).
