Double Jointed King Dee Bit

This describes an all-polymer double-jointed mouthpiece, where even the center roller is made of the same soft, flexible material as the outer bars, rather than a metal roller (like brass or copper) set into a polymer mouthpiece. It's one of the gentlest, most fully "soft" bit combinations available.

Design

• The mouthpiece has a double-jointed structure — two outer sections plus a center piece — but instead of a flat plate or metal lozenge, the center features a rotating roller made entirely of polymer.
• Both the outer bars and the roller are typically made from the same "space age" polymer, often apple-scented, giving a consistent soft, warm feel across the entire mouthpiece with no metal contact points at all (aside from the rings/cheeks themselves).
• The roller sits at the center joint and rotates freely, similar in concept to a metal roller, but softer to the touch.

Function

• Eliminates the nutcracker effect: As with any double-jointed mouthpiece, the two joints prevent the sharp folding/pinching action of a single joint, spreading pressure more evenly across the tongue and bars.
• Softer overall feel than a metal-roller version: Because the roller itself is polymer rather than metal, there's no cold, hard metal anywhere in the mouth — the entire mouthpiece experience is warm and give-y, which can matter for horses especially sensitive to or apprehensive of metal.
• Gives the tongue something to engage with: Like metal rollers (brass, copper), the polymer roller offers the horse's tongue something to play with, which can help keep a fidgety or tense mouth quieter and more settled by redirecting nervous tongue movement into a controlled, contained motion.
• Encourages acceptance: The pleasant scent and consistently soft material throughout (bars and roller alike) is aimed specifically at improving bit acceptance, especially in horses wary of metal.
• Independent side movement: The double-joint construction allows each side of the mouthpiece to move somewhat independently, offering clearer lateral and flexion cues than a single joint.
• No leverage or added severity: This remains a true snaffle, working purely through direct pressure.

What it's good for

• Horses that are particularly averse to metal, or have had negative associations with a bit: Because there's no metal anywhere in the mouthpiece (aside from any internal core, which is usually not in direct contact), this is one of the softest, most approachable options for rebuilding trust and comfort.
• Very sensitive-mouthed or apprehensive horses: The combination of a soft polymer roller and soft polymer bars minimizes hard contact points throughout the entire mouth.
• Young or green horses learning to accept a bit for the first time: The gentle, fully soft mouthpiece plus the roller's engaging quality make this an approachable, encouraging introduction to contact.
• Fidgety or "busy-mouthed" horses: The roller gives a constructive outlet for a horse that wants to move its tongue or fuss with the bit, without introducing a firmer metal element.
• Advanced or precise work where a mild mouthpiece is still needed: Some versions of this design are specifically noted as suitable for more advanced training, since the double joint still allows fairly clear, independent rein action despite the overall softness.

A note on limitations

• Because there's no metal roller and no metal center piece, this combination doesn't offer any taste-driven salivation boost the way a copper or blue steel roller would — its comfort benefit comes purely from material softness and the tongue-engaging roller action, not from taste stimulation.
• Polymer mouthpieces, including rollers, can be chewed and damaged over time, particularly by strong or persistent chewers, so periodic inspection for wear or bite marks is worthwhile (and typically not covered under warranty by manufacturers).

A note on classification

• The overall lateral action still depends on the cheek style (loose-ring, D-ring, Full Cheek, Baucher, etc.) this mouthpiece is built into.
• This combination sits at the very mild end of the spectrum, prioritizing maximum softness and acceptance over any added control or taste-based salivation boost.

Summary

A Double-Jointed Polymer bit with a polymer roller offers a fully soft, all-polymer mouthpiece experience — no metal contact points, a gentle double-jointed profile, and a roller for the tongue to engage with — making it one of the gentlest, most approachable bit combinations available, particularly well suited to horses wary of metal, very sensitive mouths, fidgety horses, or young horses just learning to accept contact.