UNMOUNTED 3/4" BRISTLE SUPER BRUSHES 1/8" HOLE MEDIUM-PACK OF 12 Feature solid-ring construction for durability and plenty of evenly distributed animal hair bristles for uniform wear. Designed to run true. Have brass hubs with 1/8" arbor holes. Can be mounted on 1/8" Screw Mandrels for flex shafts or on MK Plastic Spindles for polishing motors. Hair trim length 3/16". Max. operating speed: 25,000rpm. Made in China. Sold by the dozen.