In the hunter ring, only a select few bits are allowed to be used. In the jumpers, on the other hand, anything goes as long as it is humane.
ARTICLE G202 TACK AND EQUIPMENT
2. Bitless bridles are not permitted in the hunter ring.
3. Bridle: The bridle may be double, pelham, single (snaffle) or kimberwick. It must be leather (not rubber covered), rolled or plain and may be buckled, sewn or studded (not snapped).
4. Bits: All bits must be humane in nature. Snaffle bits may be with or without cheeks. Wire snaffle bits, either single or double are permissible. It is permissible to use a snaffle with fixed slots for cheek pieces and/or reins. Bit guards are not permissible.
5. Gimmicks: Any gimmicks (e.g. nerve lines, tongue ties, gag bits, any bit that acts as a gag, tack nose bands etc.) are illegal. Nose nets are permissible.
6. Reins: entirely leather of any description, buckled, studded or sewn; single rein pelham and pelham converters are only allowed in junior and amateur classes in 3’ (0.90m) or below. In the case of bad weather, at the discretion of the judge, steward and/or competition committee, rubber reins may be allowed.
Snaffle bits provide the rider with no leverage. You can choose any humane mouthpiece to go with the various snaffle cheeks. The most common snaffle bit in the hunter ring is the Dee-ring. It is an attractive bit while providing some help with turning with more of a loose-ring feel than you would get with a full cheek bit. Full cheek snaffles are also quite common; they provide the same guiding action as the Dee-ring but with less movement. Egg butt snaffles are sometimes seen but they are not as common as the Dee-ring or full cheek. Loose ring snaffles are rarely seen in the hunter ring. This is partly due to style and partly because they can sometimes cause pinching (bit guards are not allowed in the hunter ring).
A single-jointed Dee-ring snaffle
A full cheek snaffle with a single-jointed, single twisted wire mouthpiece.
A double-jointed loose ring snaffle
The pelham is the most common leverage bit in the hunter ring. The two reins provide the rider with the ability to vary the amount of snaffle pressure and curb pressure. The mouthpiece can be jointed or straight, and various shank lengths are available for different severities. You may only use a single set of reins (either attached directly to the bit or by using a pelham converter) if you are competing in junior or amateur hunter classes at or below 3' (0.90m) (check your local rules to be sure!). Double reins look much better while providing the ability to adjust the amount of curb used, which cannot be done with a single set of reins.
The kimberwick is not commonly seen in the open hunter ring. It is a leverage bit that is used with a single set of reins. Having only the one set of reins means that there is no option of using snaffle pressure instead of curb pressure.
The double bridle is not commonly seen in the hunter ring, either. Having both the bradoon (snaffle bit) and the curb bit allows the rider to vary the amount of pressure applied to either.
ARTICLE G1005 TACK AND EQUIPMENT
1. Only regular cavessons with snaffles, pelhams, double bridles or kimberwicks are permissible. Pelham converters allowed only in Junior "B" and "C" classes. Reins must be made entirely of leather.
The same bits that are allowed in the hunter ring are allowed in the equitation ring. The only change in the rules concerns which riders are allowed to use pelham converters.
ARTICLE G502 TACK AND EQUIPMENT
c) Reins must be attached to the bit(s) or directly to the bridle. Gags and hackamores are allowed.
Jumpers allow any bit that is used humanely. Most jumpers go in some sort of snaffle, but there are also many that go in a gag bit or a pelham, or no bit at all (a hackamore).