Reinsman Large Signature Chain & Copper Mouth Horse Bit . The Rolux Chain Competition Bit offers a larger chain link, enhanced by the Signature Copper O-Ring preferred by most horses. The chain design molds to the shape of any horse's tongue, works off of tongue, lip, bar and curb pressure and helps to lighten and re-sensitize even the heaviest of horses in any riding discipline. The curb adjustment enhances the feel and control of the chain bit and should be adjusted for the desired response. Copper is a soft metal, watch for excessive wear.