Implementation standard: Bluetooth v2.0, Bluetooth protocol: Bluetooth serial port profile (SPP) Communication rate: 4800, 9600, 19200, 38400, 57600, 115200bps Modulation mode: 2.4G direct sequence frequency hopping (FHSS) Communication distance: 5 meters (open space) Transmit power: 3dBm Acceptance sensitivity: -80dBm Working current/pairing current: 8/25mA Dimensions and weight: 78x34x16mm 29g Battery usage: 1-2 hours for full charge, 8-10 hours for full use Colour:black white Material:plastic Package Contents: 2 x BT578 serial port Bluetooth adapter 2 x DB9 female to female adapter 2 x 410mAh lithium battery (built-in) 2 x 220V-USB power adapter 2 x USB power supply charging cable Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.