Patriot Memory's Signature Line DDR3 1333MHz SODIMM for Apple computer systems delivers quality, reliability and performance that makes them the perfect memory upgrade solution. We test for compatibility in Apple iMac, MacBook, MacBook Pro and Mac Pro systems. This 4GB module is designed to run at PC3-10600 (1333MHz) at CAS 9 latency timings. Built using specific build-of-materials (BOMs) we ensure that every module meets and exceeds industry standards: offering you a hassle-free upgrade. We certify every component that goes into our modules, including the modules themselves, which must pass strict standards to ensure compatibility, quality and reliability. With free customer service and a lifetime warranty, Patriot Memory's Signature memory modules are a perfect system upgrade option.