From Amazon
Corsair CMZ4GX3M1A1600C9 Vengeance 4 GB (1 x 4 GB) DDR3 1600 Mhz C9 XMP Performance Memory Module - Black
Gadcet
Corsair CMZ4GX3M1A1600C9 Vengeance 4 GB (1 x 4 GB) DDR3 1600 Mhz C9 XMP Performance Memory Module - Black
OnBuy
Corsair CMZ4GX3M1A1600C9 Vengeance 4 GB (1 x 4 GB) DDR3 1600 Mhz C9 XMP Performance Memory Module - Black
Compadvance
CORSAIR 4 Gb Ddr3-1600