Normal NFC tags do not work when placed directly onto metal surfaces. Therefore, when using NFC tags on metal you either need to create a gap of at least 0.5 cm between the tag and the metal or you can use a special tag - called an 'on-metal' tag - which has an additional ferrite barrier material between the NFC tag and the adhesive.
On-metal tags will work on both metal and non-metal surfaces. However, on-metal tag scan distances always tend to be slightly less than standard NFC tags so unless you need tags that will (or might) go on metal, we would strongly recommend that you go with standard tags.
This is a Special Order product which we will manufacture specifically for you. Current production time is estimated at 8 weeks.