You may choose to redeem your USH against its underlying SOL value at any time. This is done by buying back the debt of a vault of your choice. Note that you will be charged a fee based on the amount redeemed as well as the collateral ratio of the vault - the higher the amount redeemed as well as the collateral ratio, the higher the fee.
This feature is offered in case USH is trading under $1 and provides a floor price guarantee.
Use this feature with caution, you will usually be better off exchanging your USH on an exchange!