1.extension rod 2.ore mining and many type 3.good price ... , 7, 11, 12 degree taper).Bit diameter: 28mm-57mm.3. Extension drilling toolsButton bit, face design: Flat face, Drop centre, Normal ... hammers and DTH bits (Down The Hole Drilling)Offer IR hammer, DHD3.5, DHD340a, DHD360, DHD380, and low pressure hammers CIR65a ... . (Rod, Cross bits, button bits and X-type bits etc). extension rod