DURABLE - Double-Sided 3/8" Heavy Duty High Speed Rotary Metal Cutting Blade Made From High-Quality Heat Resistant Steel. FAST - Quickly Separates Spot-Welded Panels Without Distortion. The cutting edge is sharper and the piercing ability is better. PERFECT SIZE - 3/8" Diameter Cutting Blade is Ideal for Removing Spot Welds.1/4" Standard Size Arbor with Flats to Eliminate Spinning in Chuck (fits 1/4" and larger drills). The cutter is wear resistance and smooth removal of scrap during operation. Save time and money with this bonus pack that includes 2 rotary spot drill with cutting blades PLUS 5 extra blades! Flexible Using- Great Spot Weld Cutter can be used for Iron, cast iron, alloy steel, carbon steel, die steel,die grinder, fix vehicle,drill holes,auto body renovations,etc anywhere you think it can be helpful.