Used Crucial 16GB (2x8GB) DDR3-1333 SODIMM
Specs:
Crucial (Micron) Memory
8GB per module
DDR3-1333
PC-10600
204 pin SODIMM
Non ECC
1.35v
Fits:
Apple iMac 21″ Mid 2011
Apple iMac 27″ Mid 2011
Apple MacBook Pro 13″/15″ 2011
Apple MacBook Pro 13″/15″ 2012 (Non retina)
CT8G3S1339M Crucial 8GB PC3-10600 DDR3-1333MHz non-ECC Unbuffered CL9 204-Pin SoDimm 1.35V Low Voltage Dual Rank Memory Module for Apple