Solar charging. Answer/end/reject a call. Voice dialing. Last call redialing. Call switching. Scroll the last 20 incoming calls. Store 200 groups telephone number. Incoming call number and English name display. Built-in high intelligent microphone. Built-in powerful speaker. With 550mAh rechargeable li-ion battery. Universal fitting systems for all steering wheels stick onto anywhere in your car. Stereo Bluetooth and FM transmitter technology. Support TF card and MP3 file format. Bluetooth specification: 2.0, range 0 -10m. Complete Bluetooth wireless installation. DSP technology. Full duplex, noise and echo suppression. Frequency range: 2.4GHz spectrum. Car charger input voltage: DC 12V-24V. Transmitter frequency: 87.5-108MHz.