StableUSD/USDS is a stablecoin designed to be pegged one-to-one with USD (1 USDS = $1 USD). This ratio is guaranteed whenever you want to purchase or redeem USDS directly with Stably, because Stably holds a one-to-one reserve of USD against all issued USDS in the market. View our latest attestation here.
On the open market (e.g. on exchanges such as Binance), this ratio may not be one-to-one, due to various market forces such as demand and available liquidity. Please be cautious if/when the price deviates from this ratio.