M42 Bi-Metal Hole Saw 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 5/8" -18UNF thread.
fitting hole saw diameter 1-1/4" to 8-17/64" (32mm to 210mm)