1,iButton RW1990 programmable 2,imported stainless steel body 3,water-proof and rust Re-Writable, Operating Voltage Range: 2.8V to 6.0V, RW1990 Can Be Read in Less Than 5ms,Working Temperature Range: -40¡ãC to +85¡ãC.imported stainless steel bodywater-proof and rust Rewritable iButton RW1990