The "TUNNA" bit has a "LOCK UP" function, that is, it does not break on the joint when the rein is pulled. This function prevents the nutcracker effect on the horse's tongue and distributes the pressure of the bit over the width of the tongue. The bit is curved and gives the tongue more space than traditional bits.   

The Tunna bit is well suited to horses that are generally unhappy with bits and try to work against the rein. The bit is made of stainless steel, is very smooth and durable and fits the horse's mouth very well.