Starrett BI Metal Cordless Smooth Cutting Hole Saws (CSC Hole Saws) are constructed of hardened heat and abrasion resisting high speed steel teeth with a tough alloy body and cap, giving exceptional strength, durability and shatter resistance. Designed for use with battery operated power tools, our CSC Hole Saws will cut twice as many holes as the equivalent standard hole saw per battery charge. Advantages:The perfect tool for on site work with battery operated power tools.Ideal for cutting stainless, tool and mild steel sheeting plus plasterboard, wood and thin plasticsComplete assembly - there is no requirement to purchase a separate arbor and pilot drill.Constant pitch teeth provide exceptionally smooth cuts. Pitch 8 teeth per 25mm/inch.Safety stop at the base of the hole saw prevents drilling beyond maximum cutting depth.Size 20mm