1,small size dia 10mm iButton DS1990A-F5 2,Unique ID number 3,imported stainless steel ... 4,water-proof and rust This is a smaller size iButton than normal F5 size, it's more compact and other ... characters are totally same.iButtons, TM Card(iButton) is sealed with stainless steel (su304-0.3), sturdy & ... to +85¡ãCWater proof.Dimension: 11.25mm*4.25mm (max) small iButtons Dia 10mm size