The sheepskin offers protection under the saddle, while the "bare," or unlined, flaps minimize bulk under the rider's leg. The flaps are quilted with a layer of poly-flex, a material that absorbs enery and eliminates bounce. Like all Mattes sheepskin pads, this features a top line that has an anatomically correct curvature with high wither and Spine-Free design to eliminate pinching or rubbing in the gullet area which can lead to back soreness. The superior sheepskin is 100% natural without chemical treatment. The extreme density of the wool, combined with its structure eliminates bounce, friction and efficiently disseminates heat and sweat. The Mattes Correction Sqaure Pads feature the Correction System, a design that can enhance saddle fit and help maintain saddle balance and straightness. The Correction System can improve saddle fit on horses who may change form throughout competition season, have physical asymmetries or other similar situations. This system uses Poly-Flex shims that are slipped into the pockets on the saddle pad to allow for adjustments to be easily made. The poly-flex material absorbs energy to eliminate bounce and is very resilient and won't bottom out like foam or other materials. The shims are 5 millimeters thick and designed to be layered, and are easily trimmed with scissors to taper the ends and create pressure-free fit it 3-4 shims are necessary. Black or White.