... About usWe are a professional manufacturer base of series of rock drilling tools, mining tools,Drill tools. Construction tools and excavating coal ... of button bits, cross bits and chisel bits with (6, 7, 11, 12 degree taper).Bit diameter: 28mm-57mm.3. Extension drilling toolsButton bit ... .8. Blast furnace tap hole drill tools. (Rod, Cross bits, button bits and X-type bits etc). 32mm button bit