Dura-Gold Pro Series 24" K-Block Sander Firm & Flex Hand Sanding Block Pad with Hook & Loop Backing and PSA Sandpaper Conversion Adapter Pad Sand AutoDura Gold Pro Series 24" K Block Sander Firm & Flex Extra Long Longboard Hand Sanding Block Pad. Uniquely designed rectangle hook & loop hand sanding block with a 2 way design system that allows it to be used with both hook & loop and PSA sandpaper sheets. Includes an attachable PSA conversion adapter pad with a vinyl face that converts the block for use with PSA pressure sensitive adhesive sandpaper sheets. K Blocks are constructed with medium