Nokia Lumia 520 8GB Unlocked GSM Dual-Core Windows 8 Smartphone - Blue Dimensions - 119.9 x 64 x 9.9 mm, 75.7 cc (4.72 x 2.52 x 0.39 in) Weight 124 g (4.37 oz) IPS LCD capacitive touchscreen, 16M colors 480 x 800 pixels, 4.0 inches (~233 ppi pixel density) 8 GB, 512 MB RAM OS - Microsoft Windows Phone 8 Unlocked cell phones are compatible with GSM carriers like AT&T and T-Mobile as well as with GSM SIM cards (e.g. H20, Straight Talk, and select prepaid carriers). Unlocked cell phones will not work with CDMA Carriers like Sprint, Verizon, Boost or Virgin.