Shenzhen Wanyi Technology Co., Ltd. is a high-tech enterprise, mainly R & D and production of air ion counter and radiation dosimeter, since its establishment in 2011 has obtained a number of patents and a number of group and national standards. The company has the ion calibration laboratory and Cs137, Co60 radiation source calibration process and radiation safety license. And launched the GM-100 series personal dosimeter, GM-300 series radiation dosimeter and MR-50 series radiation detector and radiation probe and monitoring system. The GM-300 series radiation dosimeter uses a compact design, TFT LCD display and acousto-optic and vibration alarms, and uses a variety of GM tube detectors to provide good performance for monitoring �±, �², �³ and X-ray. The GM-300 series radiation dosimeter is small in size, light in weight, easy to carry, and can be charged online. It is a multifunctional radiation safety monitoring instrument for personnel engaged in contact with isotopes or radiation devices, production and processing materials, safety radiation of import and export products, electronic equipment, personal dose monitoring and so on.