Hook-and-Loop
Affiliate link — we may earn a commissionHook-and-loop is the attachment system that holds sanding discs to the pad. It's the same concept as Velcro: tiny hooks on the pad grip loops on the back of the disc. Peel the disc off, press a new one on. Takes about 2 seconds. The alternative is PSA (pressure-sensitive adhesive), which is a peel-and-stick disc. PSA is cheaper per disc but you can't reposition or reuse a partially worn disc. Most modern sanders use hook-and-loop because the convenience justifies the slightly higher disc cost.
Why It Matters
Sanding eats through discs fast, especially at lower grits. Hook-and-loop lets you pull a disc off, check the surface, and put the same disc back on if it still has life. PSA is one-shot. Over a project, the disc savings add up.