Yezz Billy - 8GB, Dual SIM, Windows 8.1 - Unlocked GSM Smartphone (Certified Refurbished) This Certified Refurbished product is factory refurbished, shows limited or no wear, and includes all original accessories plus a 90 day warranty Display: 4.7" IPS LCD capacitive touchscreen, 16M colors, 720x1280 pixels - Asahi Dragontrail Glass Windows Phone 8.1 OS, Dual SIM, Cortana, Memory: 1GB RAM, 8GB internal - expandable via microSD slot (card not included) Includes 3 Battery Covers (Blue, Red, White) 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