A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Kingston 2 GB DDR3 SDRAM (2 x 2 GB) 1333MHz DDR3 HP594908-HR1-ELFE at Amazon .com