The new Xcortech XT501 tracer unit is one of the best and fastest tracer units on the market. This unit uses the latest technology and is capable of illuminating 1700 rounds per minute. It uses the standard CCW 14mm thread, has an auto power off feature, so it turns off after 30 mins. Economical power use, with standby mode. 15.5 cms long - requires 4 x AAA batteries