The Dee Ring is very similar in action to the Eggbutt, it will prevent pinching of the lips and gives a slightly more solid feel against the side of the face. It also prevents the bit being pulled through the mouth. The release is slower and some slight poll pressure is introduced.
The Segundo alleviates tongue pressure while keeping an even pressure on the bars of the mouth, encouraging the horse to stay light to the contact. Horses find it difficult to lean on this mouthpiece or put their tongue over the bit.