Keeping your vehicle’s brakes operating smoothly and effectively is a must. This high-quality tool helps restore your brake cylinders like a pro, ensuring your brakes operate safely by keeping the cylinders smooth allowing the pistons to work as designed. The Powerbuilt Disk Brake Cylinder Hone works best on cylinders from 1-1/4 inch to 3-1/2 inch. This tool makes it easy to hone caliper piston cylinders quickly and evenly. Attach the flexible shaft to a 3/8 inch drive power drill and the adjustable arm tension make the hone tool self-centering and self aligning allowing for use on or off the car. The supplied 2 inch #220 medium grit stones will get you started. Disk Brake Cylinder Hone works on cylinder bores with diameters of 1-1/4 inch to 3-1/2 inch. The package includes professionally written usage instructions that take you step by step through proper tool usage.