The Irwin HSS Pro Drill Bit manufactured from high quality HSS steel. They have precision ground cutting edges for fast drilling and perfect finishing, a ground flute for maximum accuracy and fast chip removal and a universal 118 point shape for drilling a wide selection of materials. The Irwin IRW10502266 HSS Pro Drillbits comes in a bulk pack of 10 with the following dimensions:Drillbit diameter: 3.5mmTotal length: 70mmWorking Length: 39mm IRWIN Hss Pro Drill Bits Bulk Pack (10) 3.5Mm Ol:70Mm Wl:39Mm in Silver