World Smallest bluetooth headset mini cellphone. Support dual sim Nano cards (or one sim+ one TF card) Band (2G): GSM 850/900/1800/1900MHz ( Sim Card must Support GSM Frequency, Recommend T-Mobile Sim Card,Not Work With At&t,Spring &Verizon Or Boost) Can be Used as a Standalone Phone or a Bluetooth Headset for Other Devices. It have a speaker and mic, so it can be used as a independent main phone when insert a regular size SIM card. Very practical to use when traveling or using as a spare cell phone in the car. Please rip off the yellow tape on the battery before use it, or it doesn't work. L8star BM10 Worlds Smallest Phone 2 in 1 Mini Phone Unlocked GSM with Hands Free Bluetooth Dialer Bluetooth Headphone Dual SIM Card GSM (White In Gray ) Brand No Brand SKU 101126230_NP-1021710769 Number Of Cameras Not Specified Wireless Charging No Headphone Jack No Fast Charging Not Specified Pre-Owned No Protection Not Specified Body Type Not Specified Notchted Display Not Specified Year Not Specified