Constructed from M42 high speed steel with 8% premium cobalt content Rigid solid steel back plate 4/6 variable pitch geometry with unique fleem ground teeth design Featuring a 1-7/8 in. depth of cut Diamond sides provide quick plug removal (available on 7/8 in. to 6 in. hole saws) Cats eye openings on solid back plate(available in 2 in. to 6 in. hole saws)