The GR-3 is the most sophisticated, commercially available satellite receiver. It is used for surveying and civil engineering. It is designed and engineered to withstand extreme temperatures, weather and rough handling in remote locations around the world. The GR-3 can track up to 36 satellites simultaneously: GPS, GLONASS and Galileo, which is now in its testing phase. The die cast magnesium I-beam construction makes it lightweight but extremely durable, and also allows the batteries to be kept in the handle.