The blue sweet iron Buster Roller mouthpiece from Bombers Bits has a 40mm roller link in the centre. This increases tongue and bar pressure, making the bit stronger than conventional double jointed bits. The double joint reduces the 'nutcracker' action associated with single joint bits, meaning the bit will not put pressure on the top of the horse's palate. The increased pressure on the bars acts to lift the head while the roller encourages the horse to soften as he plays with the roller.
The blue sweet iron mouthpiece oxidises easily, creating a warm, sweet taste in the horse's mouth. This encourages the horse to salivate, gently mouth the bit and relax his jaw, and can help horses who have difficulty accepting conventional metal bits.
Full cheeks can be useful for horses that are unsure of the bit, because the bit doesn't move around so much in the mouth as it would do with loose rings. The fixed nature of the mouthpiece can encourage the horse to stretch into the contact. The full cheeks also help to prevent pinching at the sides of the mouth.
The arms of the full cheeks assist with steering, as pressure is applied to the cheek when a turning aid is given. This can be useful for schooling and training purposes. The cheeks also ensure that the mouthpiece remains in a central position and cannot slide through the horse's mouth.
Please note that the blue will fade with use.