Aluminum oxide is durable and the most common abrasive grain Type 01 wheels are straight (also called flat) cut-off wheels, and are used for peripheral grinding Long Life wheels use a harder binder than the Free Cut wheel, for use on high-powered machines or when cutting off softer materials like brass Reinforced design helps provide safety, strength, and straight cuts Resin bonds soften under the heat of grinding, releasing dulled abrasive grains