is this suitable for a bathtub

It is classified as sink faucet on our website, the flow rate is about 1.5 GPM / 5.7 LPM. If for tub use and you require larger flow rate, it is suggested using 3/4\" pipes for plumbing connection or connecting it to the main water supplies to ensure good flow rate. But the actual flow rate still depends on the water pressure at your home.