It was an iron muzzle in an iron framework that enclosed the head. The bridle-bit (or curb-plate) was about 2 inches long and 1 inch broad, projected into the mouth and pressed down on top of the tongue. The “curb-plate” was frequently studded with spikes, so that if the tongue moved, it inflicted pain and made speaking impossible.
Wives that were seen as witches, shrews and scolds, were forced to wear a brank’s bridle, which had been locked on the head of the woman and sometimes had a ring and chain attached to it so her husband could parade her around town and the town’s people could scold her and treat her with contempt; at times smearing excrement on her and beating her, sometimes to death.
It was designed as a punishment for “shrews‘“or “scolds” — women of the lower classes whose speech was “riotous" or "troublesome".