High speed, heat resistant Carbide Steel teeth welded to a durable alloy backing and capExceptionally strong, safe, and shatter resistant.Includes:(7) Holesaws: 3/4 in, 7/8 in, 1 1/8 in, 1 1/2, 1 3/4, 2 in, 2 1/4 inA1 Hole Saw Arbor with Pilot DrillA10 Hole Saw Arbor (11/32 inch shank) with Pilot DrillA7 Ejector Spring