Surcingle

A surcingle is a strap made of leather or leather-like synthetic materials such as nylon or neoprene, sometimes with elastic, that fastens around the horse's girth.

A surcingle may be used for ground training, some types of in-hand exhibition, and over a saddle or horse pack to stabilize the rider's weight.

A basic surcingle is unpadded, attaches around the horse by means of buckles or rings, and has no other hardware.

A training surcingle, sometimes called a "roller," has many extra rings attached, running from the ribcage up to the withers area.

[1] Compared to a saddle, a surcingle allows more precise adjustment of side reins due to the placement of additional rings.