A.internal and external buttons to cooperate, fulfill all function. B. ... the stable 20mA output 4 -.5, internal and external buttons to cooperate, fulfill all function.6, batteries, outside ... shows, minutes and seconds and day to flow, bladeEisplay to display measuring different medium:“m3” Said ... down, can directly the diaphragm left, right position to operate two keys, very convenient. (3),Time ...