Trend 1307/138WS Saw forstner 1 3/8 inch diameter Short SeriesSaw Tooth Forstner bits are made from high grade Carbon Steel and meticulously heat treated. They cut fast, with the grain or across it. They can drill overlapping holes in any direction and are chosen for exacting and delicate work, such as scroll and scolloping operations. Not for use with routers.Specification-D=1 3/8 inchesD=35 mmC=57.15 mmOL=88.9 mmOL=3 1/2 inchesShank Dia=3/8 inchShank lng.=31.75 mm