The lightweight rubber nylon compound Bombers Blue mouthpiece from Bombers Bits is ported for tongue relief. This reduces tongue pressure, while applying pressure to the bars of the mouth.
This bit may be suitable for horses with large tongues, who find straight bar bits uncomfortable.
The loose rings ensure that the bit remains mobile in the horse's mouth, further promoting gentle mouthing and salivation. They also allow pressure to be released instantly when the rein aids are relaxed, thus promptly rewarding a correct response to commands.
Bomber Nel explains more about the Bombers Blue in this video:
BD AND FEI DRESSAGE LEGAL (when bit rubbers are removed).