Implementation standard: Bluetooth v2.0 Bluetooth protocol: Bluetooth serial port profile (SPP) Communication rate: 4800, 9600, 19200, 38400, 57600, 115200 bps Modulation mode: 2.4G direct sequence frequency hopping (FHSS) Communication distance: 5 meters (open space) Transmit power: 3dBm Reception sensitivity: -80dBm Working current / pairing current: 8 / 25mA Dimensions and weight: 78 x 34 x 16mm, 29g Battery: Built-in 410mAh lithium battery Charge time: 1-2 hours Usage time: 8-10 hours Color: Black, White Material: Plastic Package Contents: 1 x BT578 Serial Port Bluetooth Adapter 1 x DB9 Female to Female Adapter 1 x 410mAh Lithium Battery (Built-in) 1 x 220V to USB Power Adapter 1 x USB Charging Cable Note: The package includes only the items listed above. Other products are not included. Lighting and display differences may cause slight variations in the color of the item shown in the picture compared to the actual product. Measurement error is +/- 1-3cm.