Which of the following is NOT a type of direct pressure bit?

The direct pressure bit refers to a category of bits that operate through direct contact with the horse's mouth and provide immediate feedback to the horse. A curbed bit, on the other hand, is designed to create leverage and uses a curb chain or strap which allows for a different form of communication with the horse that involves both direct pressure and leverage.

The snaffle bit is a classic example of a direct pressure bit, as it applies direct pressure to the horse's bars and tongue when the reins are pulled. A belly strap bit also falls under this category as it works through direct pressure to give cues to the horse. A bridle bit, typically referring to a standard bit used in conjunction with a bridle, also falls within the scope of bits that can exert direct pressure.

Thus, the curbed bit does not fit the classification of direct pressure bits because its design allows for leverage, making it distinct from the others listed, which are primarily focused on direct mouth pressure without the mechanics of leverage engagement.