Pull-in and Drop-out are the points referred to when the contacts close and open. The pull-in and drop-out are specified in ampere turns (AT) or milliTesla (mT) which indicate the relative magnetic strength at these opening and closing points. For some specific applications, it is also very convenient to specify the opening and closure points in distance. Most companies measure the Reed Switches in Ampere Turns, though universally milliTesla is a more generally accepted magnetic measurement unit. MEDER is the first and only reed switch manufacturer to convert over to milliTesla, but continues to reference AT.