Brake pads: Device that makes contact with the brake disc when the driver steps on the brake pad.
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It gets worn out with time, so you should replace it periodically. They are made up of a material that maximizes the friction when it makes contact with the brake disc.
When slowly braking to stop the car, it makes an annoying metal sound. I've already changed brake discs, brake pads, bearings, anti-noises, but the noise is still there.
Check the bearings. Pick up the tires and move them upside down and you will see whether there are some failures there. There might as well be a problem in the balljoints.