The Flex XC3401 Mini 4 3/8″ Backing Plate is the factory replacement backing plate. This backing plate is designed specifically for this polisher, and creates the forced rotation that sets the FLEX apart from other dual action polishers. The secret to the Flex XC 3401 Polisher’s outstanding performance is in the backing plate. The unique design forces a true dual action motion, rather than jiggling. The backing plate’s fit and design reduce vibration and give the operator a smoother, more comfortable motion. The Flex XC3401 Mini 4 3/8″ Backing Plate is made of durable molded plastic with a urethane pad to dampen vibration and heat. Hook and loop fasteners cover the bottom of the plate from edge to edge. The size of the backing plate is 4 3/8 inches in diameter.