Technical parametre Signal receiver: Signal type Infrared and ultrosonic light Receivable area Max 100 in diagonal size Interface Microsoft standard Frequency 70Khz No. of receiver 2 Infrared receiver 1 Power supply USB 5V/100mA Working system Working software system Windows XP/Vista/Windows 7 Processor Intel Pentium or higher or Intel compatibility USB interface USB 2.0 full speed or USB1.1 Memory 512MB or higher Working environment Humidity 0-90 relative humidity+35 degree(no dew) Suggested operation tempreture 0-40 degree Writing pen specification Power supply 3.7V/180mAH Battery Chargeable Charger Interface same to earphone Key-press 2 Time for full charging 1 hour USB charging line USB+interface same to earphone(70cm) Dimention Height 130mm /diameter 15mm