This RW1990 chips we use imported one, which approved to be reliable performance than others, CMOS microcircuit is essentially an electronic carrier of the unique 64-bit digital code. The code is stored in the internal nonvolatile memory. The data exchange is performed by the protocol 1-Wire, which requires one data pin and the common pin. The microcircuit supports the function of the protocol 1-Wire of ROM search, which makes it possible for several devices to operate on one bus. This protocol determines the alteration conditions of the bus status and the time intervals during synchronization by the synchropulses cuts of the control device. Data readout and writing are performed by the junior significant bit forward. TM card, also known as touch memory, electronic ke3.5y. Stainless steel package with su304,rugged, never rust, corrosion; resistant to heat; Anti-variant; sealing strong; for security patrol, sauna door locks,electronic door locks, door intercom, card systems, identification, banking, Communications, rail transportation, transportation, and so many fields. Information ibutton RW1990 memory 64, can be repeated rubbing, write the diy code. Rewritable ibutton RW1990A-F5 read-write type of card, compatible ds1990a. Rewritable, DS1990A and TM1990A iButton, RW1990 Unique 64-bit registration Number; Built-In Multidrop Controller for 1-Wire Net; Digital identification by momentary Contact Package includes:10pcs x RW1990 Sauna Key