This Starrett Hole Saw arbor adapter fits arbors with a 1/2"-20 screw thread, allowing use of saws up to 6" (152 mm) diameter.  Not recommended for heavy duty work. Model A12. ,For California Residents:,   WARNING: Cancer & Reproductive Harm - www.P65Warnings.ca.gov,WARNING: Drilling, sawing, sanding or machining wood products can expose you to wood dust, a substance known to the State of California to cause cancer. Avoid inhaling wood dust or use a dust mask or other safeguards for personal protection. For more information go to www.P65Warnings.ca.gov/wood Starrett Hole Saw Arbor Adapter ~ A12