Used Crucial 4GB CT4GS1339M.M16FKD So-dimm for Mac
Specs
Capacity 4GB
PC3-10600
DDR3-1333
204pin So-Dimm
Fits:
Apple iMac 21″ Mid 2011
Apple iMac 27″ Mid 2011
Apple iMac 27″ Late 2012
Apple MacBook Pro 13″/15″ 2011
Apple MacBook Pro 13″/15″ 2012 (Non retina)
Fully tested working part