32GB KIT (4 x 8GB) For Apple iMac Series 2.8GHz Intel Quad-Core i7 - (21.5-Inch) (DDR3 - Mid 2011) 2.8GHz Intel Quad-Core i7 - (27-Inch) (DDR3 - Mid 2011) 3.1GHz Intel Quad-Core i5 - (27-Inch) (DDR3 - Mid 2011) 3.4GHz Intel Quad-Core i7 - (27-Inch) (DDR3 - Mid 2011). SO-DIMM DDR3 NON-ECC PC3-10600 1333MHz RAM Memory. Genuine A-Tech Brand. 32GB KIT (4 x 8GB) SO-DIMM DDR3 NON-ECC PC3-10600 1333MHz RAM Memory Genuine A-Tech Memory Lifetime Warranty Toll Free Technical Support 1-866-557-4527 Designed For Apple iMac Series. (See Compatibility List Below)