The ATM-20A is easy to use as a standard timer or can be automatically triggered by external devices for start/stop via 4mm jack sockets. The stop-clock is a high accuracy timer, with a robust construction ideal for regular use. Colour coded buttons and jack sockets make the timer extremely practical and convenient to use. 30ppm quartz crystal with a fixed calibrated capacitor of 27pF for hi-accuracy timing 15mm LCD display Quick and easy press-button action for activation of start, stop and reset Stop, start and reset actuation buttons located on the top of the timer for faster reaction times Pressing the reset button during a timing cycle displays the time elapsed 4mm jack sockets for start, stop and reset allow automatic triggering of timer by external devices Practical and convenient to use with colour coding and clear marking on buttons and jack sockets Impact-resistant ABS case with non-slip rubber feet for stability on the bench Supplied with battery