Features: Brand new and high quality Input voltage range of 5V-20VDC, power supply range for a variety of power supply occasions, students and projects to use more convenient, GPRS module communication peak- current is very large, low voltage, so the higher development board power supply voltage, current The smaller the power supply pressure, the smaller the integration of the gprs module into the product, the power board of the development board needs to be taken into account, making the power line more than 1mm wide, as short as possible. Module connected to the power automatically connected to the network- connection, no need to control the boot button, power on the direct start, eliminating the need for a boot process, set the boot pin, you can control the user to control the machine. Module TTL with level conversion circuit, compatible with a variety of single-chip serial port. Do not need to convert directly connected. Audio interface pin out the way to facilitate the test, set aside headset and microphone interface. Support TTS \ DTMF function, you can text directly through the language broadcast and call to identify each other keys, to achieve and 10086 voice function. Bluetooth-compatible 3.0 protocol, enhanced BT antenna signal super, support for serial port SPP and audio services. Reserved lithium battery-powered BAT interface, you can use lithium battery-powered, easy engineering development, 3.7V lithium battery or 18650 lithium battery. Reserved IPEX interface, SMA interface, spring antenna interface, can be used for different occasions, different antennas. Specifications: Material: PCB Size: 52x43mm Package Includes: 1 x SIM800C Development Board note: Please allow 0-1cm error due to manual measurement. pls make sure you do not mind before you bid. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!