Wireless Projection Bluetooth Virtual Keyboard for Smartphone and Tablets Item Type: Bluetooth Virtual Keyboard Material: ABS Color: White Keyboard light source: red diode Keyboard layout: Approximately .19mm bevel, size is QWERTY layout Product Size: 250mm (W)x110mm (H) Keyboard position: about 100mm keyboard device Required projection surface: Non reflective, opaque plane Recognition rate: more than 350 characters per minute Operating surface: Any opaque surface Physical size: 38mm x 75mm x 18mm Weight: About 47 grams Power supply: USB power supply, lower 1A 5V Battery capacity: polymer battery, maximum 1000mAH (maximum), 3.7V battery operation Time: 120 minutes Battery charging time: 200 minutes USB interface: USB 1.1 and 2.0. USB HID version 1.0 BT: V3.0 (Class 2), HID profile version. 1.0 Frequency range: 2402-2480MHz Channel: 79 Modulation: GFSK Working temperature: about -10-40°C Storage temperature: about -20-40°C