nostr:npub1y8m4cgy8s4zx22g9krgvml0nuh8s2kva3advpfua6wpcqhrywkvqndkmzd will explain you

This is a keychain that integrates an NFC Type 2 chip and an LED. For cards used with wallets, NFC Type 4 would be more suitable.

I made this as a general-purpose gadget. If you want to use it to store business cards, links, or messages, it can definitely be done. It depends on how you want to apply it and what kind of links or data you want to store on the card.

Here’s some information about the differences between NFC Type 2 and NFC Type 4:

https://stackoverflow.com/questions/29596521/difference-between-nfc-forum-tag-2-and-nfc-forum-tag-4