Silicon Power 8GB (4GBx2) DDR3 1066MHz (PC3 8500) 204-pin CL7 1.5V SODIMM Laptop Memory Module 4GB DDR3 laptop module that operates at speeds up to 1066 MT/s and has a CL7 latency. 100% tested for stability, durability and compatibility. Original and high quality memory module. Backed by a lifetime warranty to promise complete services and technical support. **Not competitable with MacBook Pro version before 9.1