Corsair CMSA8GX3M2A1333C9 Apple Certified 8GB (2x4GB) DDR3 1333 MHz (PC3 10666) Laptop Memory 1.5V Capacity: 8GB (2 x 4GB) Speed: 133MHz CL9; Timing: 9-9-9-24 (1333MHz); Pin Out: 204 Pin Voltage 1.5V; Latency: CAS 9, Lifetime Warranty Tested at Apple compatibility lab to ensure functionality with all current DDR3-based MacBook Pro, iMac, and Macbook Compatible with MacBook Pro (13-inch, Late 2011), MacBook Pro (13-inch, Early 2011), MacBook Pro (15-inch, Late 2011),MacBook Pro (15-inch, Early 2011), MacBook Pro (17-inch, Late 2011), MacBook Pro (17-inch, Early 2011) Memory Type: DDR3; Speed: 1333MHz