Corsair Apple Certified 4GB (1x4GB) DDR3 1333 MHz (PC3 10666) Laptop Memory (CMSA4GX3M1A1333C9)

• Capacity: 1 x 4GB
• Speed: 1333MHz CL9
• Timing: 9-9-9-24 (1333 MHz)
• Pin Out: 204 Pin
• Voltage: 1.5V
• Latency: CAS 9
• Lifetime Warranty
• Tested at Apples compatibility lab to ensure functionality with all current DDR3 based Macbook Pro, iMac, and Macbooks

Both memory modules arrived on time and in excellent shape. Review is written many months after purchase of product. Modules are good. I'd recommend Corsair memory if you're a little strapped for cash, otherwise, spend your money on higher quality memory.