Dura-Gold Pro Series Rigid Longboard Hand Sanding File Block, Both Hook & Loop Backing and PSA Backing Conversion Adapter Pad, Rolls 16-1/2" SandpaperDura Gold Pro Series Rigid Longboard Hand Sanding File Block. Uniquely designed hook & loop longboard hand sanding file block with a 2 way design system that allows it to be used with both hook & loop and PSA longboard sandpaper sheets or rolls. Includes an attachable PSA conversion adapter pad with a vinyl face that converts the longboard file block for use with PSA pressure sensitive adhesive sandpaper sheets. An ideal high performance paint