The crupper is used to prevent the harness saddle from moving forward, this model is made from double layer, stitched polyweb. It features a soft padded dock lined with anti-gall material, and loops in the backband, designed to hold the breeching straps in the correct position. The measurement includes the dock ShetlandMinimum Length: 60cm (23 3/4")Maximum Length: 80cm (31 1/2")PonyMinimum Length: 75cm (29 1/2")Maximum Length: 95cm (37 1/2")CobMinimum Length: 85cm (33 1/2")Maximum Length: 105cm (41 1/2")FullMinimum Length: 100cm (39 1/2")Maximum Length: 120cm (47 1/2")XFullMinimum Length: 105cm (41 1/2")Maximum Length: 125cm (49 1/2") What is a Crupper? For driving, a crupper is used to prevent the parts of a harness that fit around the barrel of the horse (the girth, bellyband, back band and saddle) from slipping forward. The crupper is adjusted to allow about an inch of play between the crupper and the dock. Where breeching is used the crupper also anchors the loin straps.