RAM & Memory Upgrades
8GB (2 x 4GB) DDR3 1333MHz PC3-10600 204-PIN SODIMM MEMORY RAM KIT COMPATIBLE WITH MACBOOK PRO (EARLY/LATE 2011)
SIZE/CAPACITY: 8GB KIT (2 x 4GB) VOLTAGE/POWER CONSUMPTION: 1.5v CAS LATENCY: CL9 SPEED: PC3-10600 (1333MHz) TYPE/INTERFACE: 204-PIN DDR3 SODIMM 204-PIN MACBOOK & MACBOOK PRO DDR3 SODIMM
https://www.bizrate.co.uk/ram_memoryupgrades/8gb-2-x-4gb-ddr3-oid6611059798.html