> ## Documentation Index
> Fetch the complete documentation index at: https://docs.optimism.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Enable span batches

> Learn how to enable span batches on your OP Stack chain by confirming Delta activation and configuring the batch type on op-batcher.

Span batches encode a span of consecutive L2 blocks in a single batch, reducing the overhead of batch submission.
This is especially beneficial for sparse, low-throughput chains.
The format was introduced in the Delta network upgrade, and chains opt into it through the `op-batcher` configuration.
For background on what span batches are and why they exist, see [Span batches](/op-stack/features/span-batches).

## Before you begin

Span batches are only valid once the Delta upgrade is active on your chain.
The `op-node` derivation pipeline drops any span batch whose L1 origin predates Delta activation, logging `dropping span batch before Delta activation`.

<Warning>
  Do not enable span batches on the batcher before Delta is active on your chain.
  Verifier nodes will drop the span batches your batcher posts, so the data you pay to submit will not advance the safe chain.
</Warning>

## Enable span batches

<Steps>
  <Step title="Confirm Delta is active on your chain">
    Delta activation is recorded as `delta_time` in your chain's rollup configuration (the `rollup.json` file passed to `op-node`).
    Delta is active once `delta_time` is set and the L2 block timestamp has passed that value.

    You can read it from the rollup configuration file directly, or query a running `op-node`:

    ```bash theme={null}
    cast rpc --rpc-url <OP_NODE_RPC_URL> optimism_rollupConfig | jq .delta_time
    ```

    If the result is a timestamp in the past, Delta is active.
    If it is `null`, Delta is not scheduled on your chain and must be activated first.
    For new chains, the `l2GenesisDeltaTimeOffset` deploy configuration parameter schedules Delta relative to genesis (`0` activates it at genesis) — see the [rollup deployment configuration reference](/chain-operators/guides/configuration/rollup).
    For Delta activation times on OP Mainnet and OP Sepolia, see [Network upgrades](/op-stack/protocol/network-upgrades).
  </Step>

  <Step title="Set the batch type on op-batcher">
    The `op-batcher` `--batch-type` flag (environment variable `OP_BATCHER_BATCH_TYPE`) selects the batch format: `0` for singular batches (the default) and `1` for span batches.

    Set it to `1` and restart the batcher:

    ```bash theme={null}
    --batch-type=1
    ```

    or, as an environment variable:

    ```bash theme={null}
    OP_BATCHER_BATCH_TYPE=1
    ```

    Optionally, `--max-blocks-per-span-batch` (`OP_BATCHER_MAX_BLOCKS_PER_SPAN_BATCH`) caps the number of L2 blocks added to a single span batch.
    The default is `0`, which means no maximum.
    See the [batcher configuration reference](/chain-operators/reference/batcher-configuration) for details on both flags.
  </Step>

  <Step title="Verify the batcher configuration">
    On startup, the batcher logs its channel configuration.
    Check the `Initialized channel-config` log line and confirm it reports `batch_type=1`:

    ```text theme={null}
    INFO [...] Initialized channel-config ... batch_type=1 ...
    ```
  </Step>
</Steps>

## Revert to singular batches

Singular batches remain valid after Delta, so you can switch back at any time by setting `--batch-type=0` (or unsetting `OP_BATCHER_BATCH_TYPE`, since `0` is the default) and restarting the batcher.

## Next steps

* Learn what span batches are and how the format works in the [span batches explainer](/op-stack/features/span-batches).
* Review the other batcher settings that affect cost and stability in [Configure the batcher](/chain-operators/guides/configuration/batcher).
* Read the [span batches specification](https://specs.optimism.io/protocol/delta/span-batches.html?utm_source=op-docs\&utm_medium=docs) for the full format definition.