Samsung ram memory 4GB (1 x 4GB) DDR3 PC3L-12800,1600MHz, 204 PIN SODIMM for laptops : Amazon.in: Computers & Accessories
SK Hynix 4GB HMT451S6AFR8A-PB DDR3 1Rx8 PC3L-12800S Laptop Memory at Amazon.com
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