# Extending the Hook (/docs/protocols/uniswap-labs-hooks/erc4626-wrapper/concepts/extending-the-hook)

Learn the narrow seams ERC4626WrapperHook exposes for subclasses, including the overridable unwrap source.

`ERC4626WrapperHook` is designed to be subclassed at narrow seams:

* `_redeemToUnderlying(wrappedAmount)` is the overridable source of the unwrap leg. The default redeems directly from the vault. A subclass can add fallback sourcing, for example forcing liquidity back into a vault that keeps most assets deployed, while leaving the share `take`, the settle-to-`PoolManager` tail, and all accounting unchanged. The contract holds the shares on entry and must hold the received underlying on return.
* `_deposit`, the preview helpers, and `_supportsExactOutput` / `_supportsExactInput` are `virtual` for further specialization.