The Mattes Correction Pad system is ideal for horses that are either out of shape/from or returning from an injury, where incremental correction may be needed as the horse's back and shoulders gain muscle tone.  It is also good for one-sided horses or as a rear or front riser. Unique design of the Mattes Correction Pad incorporates four pockets along the spine (2 front and 2 back). Shims (12 included) fit into these pockets for a completely custom fit.  As the horse gains muscle you can remove the shims one by one to give him room to muscle up into the saddle. This pad has a heavy-duty outer cotton quilt , with a patented Mattes stitching pattern.