CAT Retention Knobs are manufactured from aircraft quality AMS-6274 alloy steel and are hardened for maximum longevity. Match the dimensions and appearance of your retention knob to the drawings below. Use the manufacturer’s print that came with your machine to verify your selection. For safe operation, ensure the pull stud you order is the exact pull stud your machine uses. Using the wrong pull stud can cause damage to the spindle and/or toolholder, and can create a safety hazard.