... -90AType:1990A-TM Button,global unique ID(unmodifiable)Physical:Electronic chip stored in the stainless steel case that is water-resistant ... ,great concealed,waterproof,Long life>20yearsPatrolmanHUA-90BType:1990A-TMPhysical:Electronic chip stored in the stainless steel case ,water-resistant.strong & durable ... issue, Inventory, Asset tracking etc... Unique Security Guard tour system/contact model