Walthers Cornerstone Horn-Hook Couplers are direct replacements for the older-style X-2F couplers in Walthers rolling stock kits. Couplers are molded in Delrin(R) plastic. Horn-Hook Couplers will not couple to knuckle couplers. Fits rolling stock with older-style horn-hook couplers Direct replacement for couplers in Walthers rolling stock kits Molded in Delrin(R) plastic 12 per pack