Inserts, also referred to as a chuck liner, is the mechanism that grips the bottle cap and screws it on. Inserts are available in several materials that have different gripping properties.  

Aluminum driver shells thread onto all Swan-Matic Capping Machines and accept replaceable urethane, vinyl, and rubber inserts.

More questions?  What is an insert? 

 Insert Sizing Chart

What is Durometer?

The Durometer is the international standard for measuring the hardness of rubber, plastic and other NON-METALLIC materials. A durometer tool measures a compound's susceptibility to indentation, which should not be confused with durability or tensile strength as there is no inherent relationship across all compounds. Durometers are described in the American Society for Testing and Materials specification ASTM D2240. There are a variety of Durometer scales. Our products are measured using the "Shore A" Scale