3M’s back up pad is designed with 3M abrasive discs. The pad has a 5/8″ thread and is 125mm in diameter. The pad is a durable foam that will not break down or degrade with use. The pad’s construction allows it to conform to the surface being worked on, providing a uniform finish. 3M’s back up pad is essential for any mechanic or body shop. It is a must-have for anyone who uses 3M abrasive discs.