5/16" x 3/4" x 1/4" Shank. The double cut burr allows for rapid stock removal in the harder materials. The chisel tooth pattern not only minimises tool chatter but reduces the chip to a granular shape, in most materials, thereby reducing or eliminating the sharp sliver chips that are normally experienced. This chip reduction also helps eliminate loading of the flutes. An improvement in tool control will be realised as the double cut tends to reduce the pulling action of the main flute pattern.