Base's Denim upgrade is now live on mainnet, cutting block time to 200 milliseconds and enabling the network to produce five full blocks per second. The upgrade replaces the previous Flashblocks preconfirmations with native blocks, each carrying its own block number, hash, state root, and receipts. Denim also introduces BaseTime, allowing smart contracts to achieve millisecond-level time precision while keeping block.timestamp in seconds. Additionally, the B20 token standard has been improved so issuers can require every transfer to be approved by a designated party such as a transfer agent, and reuse the same address list as either a whitelist or blacklist.