This is a set of three replacement coarse grit stones and cotter pins for Powerbuilt product #648439 or another cylinder hone deglazer. These high-quality 4" coarse grit stones (#120) are designed to deglaze engines on a cylinder hone. Set also includes corresponding cotter pins.This automotive specialty tool from Powerbuilt will help make the job at hand easier and quicker whether you are a seasoned professional or a casual weekend mechanic. Dependable Powerbuilt specialty tools offer power, precision and style. They meet or exceed applicable ANSI standards at affordable prices.