Lip strap
A lip strap is a piece of horse tack made of rolled leather or occasionally thin chain, used sometimes on some types of English-style curb and pelham bits. The lip strap runs between the bit shanks and passes through a special center ring on a curb chain sometimes called the "fly link". The lip strap attaches to rings at midpoint of the shanks and buckles on the near side. The lip strap helps keep a "mouthy" horse from mouthing or "lipping" the shank. It also helps prevent the curb chain from unfastening or otherwise moving too much . In western riding, the "slobber bar" or "shank hobble" placed between the rein rings of a curb bit serves the same purpose as a lip strap. The leather curb strap-like attachments that are sometimes used to connect the rings of snaffle bit on a western bridle are also occasionally known as lip straps, though "bit hobble" is the term more often used. References.