OWC 4.0GB UPGRADE: Consists of a 4GB DDR3 1333MHz PC3-10600 CL9 SO-DIMM 1.5V 204-pin Memory Module Compatible with Mac and PC 100% COMPLIANT: With JEDEC Standard Specifications, ROHS Compliant, Warranty Safe Upgrade. Designed and Tested to Meet or Exceed All MAC Specifications for iMac and PC Laptops COMPATIBLE WITH: iMac Models: Mid 2011 27 inch iMac (Model ID: iMac12,2); Mid 2010 27-inch iMac (Model ID: iMac11,3); Late 2011 21.5-inch (iMac Model ID: iMac12,1); Mid 2011 21.5-inch iMac (Model ID: iMac12,1); and Mid 2010 21.5-inch iMac (Model ID: iMac11,2) COMPATIBLE WITH: Mac mini: Mid 2011 Model ID: Macmini5,1 & Macmini5,2 and Mid 2011 Server Model ID: Macmini5,3 and MacBook Pro: 13inch, 15inch, 17inch 2011 Models: MacBookPro8,3 MacBookPro8,2 MacBookPro8,1 COMPATIBLE PART NUMBERS: 661-5861, 661-6141, 661-5962, 661-5939, 661-5529, CT2K4G3S1339M, CT2KIT51264BF1339, KVR1333D3S9/4G, KTA-MB1333/4G, M471B5273CH0‐CH9, M471B5273DH0‐CH9, HMT351A7CFR8A‐H9, HMT351S6BFR8C‐H9, HMT351S6CFR8C‐H9 INDUSTRY LEADING: Consumer Friendly Advanced Replacement Program and Limited Lifetime Warranty, which Includes Free Tech Support by Other World Computing