This is for installation in the 78100 and 78110 roller test stands. It allows you to measure duration of operation, time, and speed. A special pair of roller brackets with a measurement transducer is included with connections to the display unit with an LCD display. The unit is operated with 3 type AA/LR6 batteries (not included). Dimensions 80 x 70 x 120 mm / 3-1/8" x 2-3/4" x 4-3/4".