Replacement chin straps of various lengths are available to you; when a horse has a very wide face, they will sometimes need a longer strap or when the horse has a narrow face it will need a smaller strap.
These straps double over themselves, so are half of these measurements. Also these measurements do not include the length of the nose piece that connects to the chin strap.
Large halter throat pieces are now available and can be used with medium halters and are needed for some horses with longer noses. These throat pieces are 6" vs. medium throat pieces, which are 5". This allows the chin & nose pieces to be positioned for a proper fit on your horse. You may also order a 5" throat piece, if needed.