Samsung Galaxy S II Skyrocket I727 16GB Unlocked GSM 4G LTE Smartphone - Black 2G: GSM 850 / 900 / 1800 / 1900, 3G: HSDPA 850 / 1900 / 2100, 4G: LTE 700 MHz Class 17 / 1700 / 2100 Android v4.1.2 (Jelly Bean) OS, Dual-core 1.5 GHz Scorpion Processor, Chipset: Qualcomm MSM8260 Snapdragon 4.5" Super AMOLED Plus Multi-Touchscreen w/ TouchWiz UI v4.0 8 Megapixel Camera (3264 x 2448 pixels) w/ LED Flash + Front-Facing 2 Megapixel Camera 16GB storage, 1GB RAM + microSD Slot Expandable up to 32GB 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.