# BTH key mechanics.

* We have created a separate smart contract for each type of key.
* Chosen network - Polygon, token standard ERC-721.
* We use DAO voting mechanics.
* We mint BTH (user keys/cards) from each smart contract.
* Cross-chain support for 18 blockchains.
* We use Metamask wallet for authorization, and upon authorization, we check the wallet ID. If the wallet owns BTH, then access is granted with the corresponding level.
* The "Learn-and-Earn" reward mechanism.
* Developed web-3 custom node cross-chain protocol, NFT authentication service on Polygon.

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