The pack saddle consists of a tree, or the wooden blocks that sit on the horse's back, the half breed which is the canvas saddle cover, the breeching and often a crupper which prevents the loaded saddle from sliding too far forward and the breast collar which holds the loaded saddle from sliding too far back on the packhorse or mule.
Since the pack saddle is not intended to support a human rider, the upper side of the pack saddle resembles a rack to let its load rest on and be tied on with ropes, straps, a surcingle or other devices.
There are several designs of pack saddles. The Cross Buck has crossed wooden bars to attach sling ropes. The army style of pack saddle has two large metal hooks each side for hanging pack bags. The Decker style has two rings for tying sling ropes.