Big Dragon E9600-XEON Mini Precision Chrono is now available at Airsoft Park for US$78.99 with free shipping. It has a rechargeable battery so no need to worry about carrying more batteries as long as it does not run out of juice in the field. It can measure muzzle velocity, firing kinetic energy, shooting distance, and can operate at -10 degress to +50 degrees celcius centigrade. It may measure rounds per minute (RPM) as seen at its faceplate. Check the product out by clicking on the image below: