Quick Change Disc Backup Pad Adapter, Abrasive Mounting Connector Size 1/4 In.-20, Abrasive Mounting Connector Type Threaded Hole, Tool Mounting Connector Size 1/4 in, Tool Mounting Connector Type Straight Shank, Overall Length 4 5/8 in, Product Type TR Quick-Change Disc Backup Pad Adapter, Compatible Wheel Diameter (Maximum) 4 in, Compatible Wheel Diameter (Minimum) 3/4 in, Compatible Wheel Thickness (Maximum) Not Applicable, Compatible Wheel Thickness (Minimum) Not Applicable