Dallas iButton tag TM1990

Dallas iButton is the name of a type of passive tag that is built into a small, rugged stainless steel container shaped like a button. This makes it suitable for many control purposes – including access control and payment at car washes. The chip in an iButton has a unique number that cannot be changed, preventing unauthorized copying. In this respect, iButtons are similar to RFID tags, but the iButton tag is only read by electrical contact – and not by radio signals.