Numerous turning projects require a jam chuck however hand turning the chuck is time consuming and not always accurate. This system solves the jam chuck problem. Insert the system s tough rubber chuck into your work then expand it by turning a nut to conveniently secure the workpiece. This remarkable package includes five chucks plus the Forstner bits to drill the jam chuck holes. Chuck and Bit sizes are 3/4", 1", 1-1/4", 1-1/2", and 2".