As show in the image,The teeth of our hole saws are Curved,this design to guarantee for longer life.This is the main superiority of our hole saws.

• Can be used in portable electric or pneumatic tools, vertical drillmachines, and other machine tools.
• For heavyduty cutting in steel plate, pipes, aluminum, cuprum, hardwood, plywood and plastics.
• The set includes 7/8"(22mm)1-1/8"(29mm),1-3/8"(35mm),1-3/4"(44mm),2"(51mm),2-1/ 2"(57mm) Bi-Metal Hole Saws, 2PC Matching Arbor .
• DoubleTooth designed to strengthen each tooth for longer life and improved durability.
• Sharper Tooth Geometry cuts material faster for faster drilling.
• Increased high speed steel height (highest in the industry) improves hole saw durability      
• Open eyelets provide for easier removal of cut materials andincreased visibility while cutting.
• Thick, hardened backing plates prevent thread stripping.