Morse.
177191 MHS Advanced Hole Saw, 1-3/16 in dia, 1-15/16 in D Cutting, M42 HSS-Co 8 Cutting Edge, 1/2-20 M. Morse Hole Saw, Advanced, Series: MHS, 1-3/16 in dia, 1-15/16 in Cutting Depth, 5/6 TPI, 1/2-20 Arbor, 1/4 in dia x 3-3/32 in L Drill, M42 HSS-Co 8 Cutting Edge, Bi-Metal Body, Toothed Cutting Edge, 145 to 425 RPM, 1/4 in, 3/8 in Chuck, Hex Shank, 1/4 in, 3/8 in Shank, Use Arbor: Ma24 and Ma34, Red, Applicable Materials: Machinable Metal, Nail Embedded Wood, Plastic, Stainless Steel Alloy and WoodThe All New Advanced Bi-Metal Hole Saw by M.