Frax Staked Ether (SFRXETH) is a liquid staking derivative and ERC-4626 vault designed to accumulate staking returns from Frax ETH validators. It allows users to earn rewards by exchanging frxETH for sfrxETH, whose value increases over time as rewards are added to the vault. This allows users to exchange their sfrxETH for more frxETH than they initially deposited.