Designed to work with standard sanding belts, they keep the belt tensioned firmly between two ends of a sturdy fiberglass bow. Large knobs at either end let you use a comfortable two-handed grip, helping prevent hand strain when sanding vigorously. The small bow is about 10″ long and the large is about 16″. Each bow comes with one 2″ x 36″ 120x belt, but you can use any 1″ or 2″ wide belt or abrasive strip in any grit, provided it is of suitable length (minimum 18″ for the small and 24″ for the large). Visit www.LeeValleyTools.com for more information.