Jobber drills are the most widely used type of drill in industry for drilling cylindrical holes. Generally they come with two spiral flutes, straight (or parallel) shanks and an overall length which varies with diameter. There are a number of variations in tool geometry, material specifications and coatings which help to optimize performance and tool life in specific applications. High speed steel drills are appropriate to most materials including steel, non-ferrous metals, plastic and wood. Carbide drills may be necessary for extremely hard materials, high temperature alloys etc. (see page 5 of our catalog for the Optimum Choice Drill Selection guide). For best results always use recommended speeds, feeds and lubricants.