There are many types of milling cutters each with their own purpose and application. End mills are tools which have cutting teeth on the end as well as running the length of the cutter. The term endmill is generally used to refer to flat bottomed cutters, but also include rounded cutters which are sometimes referred to as ball nosed and radiused cutters. These cutters are normally made from high speed steel or carbide, and have one or more flutes. These cutters are the most commonly used cutters on a vertical milling machine. Slot drills are centre-cutting endmills, generally two fluted, that are capable of cutting downwards or plunge-cutting straight down into the material and then moving laterally to cut a slot. The plunge action is only possible because at least one of the teeth extends across the centre of the cutters face. Such an operation using an end mill is impossible because of the cutters teeth arrangement, having a recess in the centre of the face. The term slot drill is usually assumed to mean a two fluted, flat bottomed endmill if no other information is available.