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

• 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, plywoodand, plastics.
• The set includes 7/8"(22mm), 1"(25mm), 1-1/8"(29mm), 1-1/2"(38mm), 1-3/4"(44mm), 2-1/8"(54mm), 2-1/2"(67mm) Bi-Metal Hole Saws, 2PC Matching Arbors and 1PC Matching Adapter.
  
• 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) improveshole saw durability      
• Open eyelets provide for easier removal of cut materials andincreased visibility while cutting.
• Thick, hardened backing plates prevent thread stripping.