The vibration of the strings is transmitted to a soundboard by a bridge over which the strings are stretched; the soundboard amplifies the sound and influences its tone nice. The hammers that strike the strings are affixed to a mechanism resting at the far ends of the keys; hammer and mechanism compose the “motion.” The feature of the mechanism is to boost up the movement of the hammer, catch it because it rebounds from the strings, and keep it in function for the next assault. Modern hammers are included with felt; in advance, leather changed into used. Visit here