These sanders are designed to follow changes in contours in high crown shapes. Full abrasive contact prevents “flat spotting”. The 15″ and 21″ sanders work with our 2-3/4″ wide pressure sensitive adhesive (PSA) sheet abrasive to form the most versatile sanding tool available! Stainless faceplate is embedded into the urethane foam body. Removing any or all of the three rods encased in the handle adjusts the flexibility of your sander to maintain complete surface contact on flat or curved surfaces. Made in the USA.