The medieval "Scold's Bridle", with two hinged sections that lock over and around the head to hold a gag in place: also serves as a devastatingly effective tethering restraint using the D-ring on the top of the head or in front of the mouth.
Available with rubber pear gag as standard, other gags - from the historically original spiked steel tab to a rubber penis - to order. Padlock fastening only. Painted steel or "antique finish" (hammered and fire-darkened).
Measure: around and over head, supplied with small range of adjustment.