Bi-Metal Hole saws take the form of a short open cylinder with saw-teeth on the open edge, used for making relatively large holes in thin material. They remove material only from the edge of the hole, cutting out an intact disc of material, unlike many drills which remove all material in the interior of the hole.
Adjustable Arbor For Hole Saw
3/8" hex shank,with 1/20" -20UNF thread.
Fitting Hole Saw Diameter 9/16" to 1-3/16" (14mm to 30mm)