Designed for professional use, the Heavy Duty Circle Cutter will make clean cuts from 1-3/4 to 7-7/8 inch diameter. The tempered steel body features marked graduations on the beam for fast measurement and application. #55 Heavy Duty Circle cutter is designed with a 1/2 shank for drill press use only; Maximum safe speed is 500 RPM. This round shank circle cutter is great for making smooth cuts through most materials, including wood, composite, sheet metal and more; Shank is 1/2 inch round. All adjusments are made with a hex wrench which is included; Replacement blade is General Tools Model # 55 Blade, replacement drill is General Tools Model # 5/6/55 Drill.
From the Manufacturer
Works like an adjustable hole saw. This heavy-duty circle cutter most preferred by professionals. 1/2 round shank for drill press use. Replaceable 1/4" high-speed tool steel bit and replaceable 1/4" pilot drill. Capacity 1-3/4" to 7-7/8".