1.Aircraft extension drill bits are used for drilling deep holes or drilling holes in the places hard to reach. 6 inches and 12 inches overall length bits are available 2.Quality high speed steel ensures the bits super hard, sharp and cutting effectively with impressive cutting performance in metal, plastic, and wood etc with long tool life 3.All drill dimensional & tolerances conform to ASME/ANSI B94.11M drill standards or USCTI - United States Cutting Tool Institute (formerly MCTI). Fractional Sizes 1/16' to 1/2' diameter are available 4.Fully ground process and precision surface finish ensure excellent chips moving, and 135 deg chisel angle with split point provide accuracy start for quick penetration without Walking and less Logging Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.