Aerator
The screw-on screen at the tip of a faucet that mixes air into the stream.
A faucet aerator is the small screen-and-housing that threads onto the end of a faucet spout. It blends air into the water to give a steady, splash-free stream while saving water. Aerators slowly clog with mineral scale and grit, which weakens flow and skews the spray. Unscrew it by hand or with tape-wrapped pliers, rinse and soak it in vinegar to dissolve scale, then thread it back on — the fix for most cases of one faucet running weak.