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 2 Arm 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 makes the honing tool self-centering and self-aligning, allowing for use on or off the car. The two supplied 1-1/8 inch #220 medium grit stones will get you started. Disk Brake Cylinder Hone works best on cylinder bores with diameters of 3/4 inch to 2 1/4 inches. The package includes professionally written usage instructions that take you step by step through proper tool usage.