The regular NFC Tags or NFC labels do not work if placed on metal. These special NFC tags can be applied on the metal surfaces, because they are with a layer of ferries that protects the magnetic fiels. Do you know why the NFC tags can not work on the metal ? Because NFC Tags work by electromagnetic induction, metal inviroment can interfere the it and reduces the performance of the NFC TAGS s antenna,effectively and stopping it creating the current needed to power the chup. Then we use a specail “an-ti metal” layer on the tag. It is a ferrite foil barrier between the tag and the adhesive layer. So we called it on-metal NFC tags .