Aluminum driver shells thread onto all Cap-Master Capping Machines and accept replaceable urethane, vinyl, and rubber inserts. A complete range of cap driver shells and renewable driver inserts are kept IN-STOCK. Send sample caps and containers to our engineers at Automation Devices and they will recommend an affordable solution to your cap tightening problem. Occasionally, applications call for a special product. Swan-Matic regularly custom engineers capping equipment to meet the needs of customer's applications. Contact Swan-Matic to see if a serrated shell will best suit your application.