Elliptical Lock Up bit from Bombers.

Loose rings provide direct contact with immediate release where the pressure on the tongue and bars ceases as soon as the rider releases the rein, and the bit assumes a neutral position in the horse's mouth. Elliptical Lock Up is a three-piece mouthpiece with a locked, elliptically shaped center part, which prevents the nutcracker effect. It applies less pressure on the bars, but more on the tongue. Elliptical Lock Up is therefore a softer alternative than the regular Elliptical, but stronger than a Control Plate.