This economically priced tester Model QMT-01 will check for the crystal pulsating without taking the back off of the watch. With the incluede test probes the watch cell and coil can be checked fro proper function as well as providing you with a constant 1.5 volt power supply. Unit measures: 5" X 5 3/4" and includes instructions. Requires 3 "AA" batteries. Made in India.