The D ring is designed to aid steering, but does not have the cheek pressure that the full cheek has. The D ring is sometimes used instead of an eggbutt to stop the bit cheeks slipping into the mouth, when turning.
The shape of the ring provides a quiet and neutral position in the horses mouth. Therefore this bit is wonderful for young or inexperienced horses. They receive optimal lateral support and guidance through the rings.
Soft very supple and pleasant in the mouth with a flexible steel core giving high security, particularly for sensitive or young horse
Hard/firm - the material is firm and no-flexible whilst very pleasant in the mouth, for very strong or horses that lean. A less cumbersome alternative to Vulcanite.