OWC 4GB DDR3 ECC PC10600 1333MHz DIMM Memory Upgrade Module Compatible with Mac Pro 2009-2012 (OWC1333D3ECC4GB) at Amazon.com
Apple 10SOPAIR4GB 4.0GB (2 x 2GB) Factory... at MacSales.com
A-Tech 16GB (4x4GB) RAM for Apple iMac (Mid 2010, Mid 2011, Late 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Amazon.com: Timetec 4GB Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac (Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) SODIMM MAC RAM Upgrade : Electronics
Kingston Technology 4GB 1333MHz DDR3 Single Rank SODIMM Memory for Apple Laptops (KTA-MB1333S/4G) at Amazon.com