Bridge UB

Where your UB actually goes

UB is one token with a ledger on Ethereum and two mirrors. Bridging out of Ethereum locks your UB in an adapter contract there and mints the same amount on the destination chain; bridging back burns it and releases the original. Between BNB Smart Chain and Base it is burn on one side, mint on the other. Messages are carried by LayerZero as an OFT, so there is no third-party custodian holding a pool and no wrapped asset with a different contract on the other side.

This is also why adding up the supply figures on all three explorers comes to more than 10 billion. The UB locked on Ethereum still exists on Ethereum while its mirror circulates elsewhere, so it is counted twice by anyone totalling the chains. Circulating supply is the Ethereum figure.

What a transfer costs

You pay gas on the source chain plus a LayerZero message fee, quoted before you sign. Overpayment is refunded to your address once the destination settles. Sending from Ethereum needs an ERC-20 approval first, because the adapter is a separate contract from the token; on BNB Smart Chain and Base the token is the bridge contract, so there is nothing to approve.

Contracts

Supply, the audit and what UB is for are on the token page.