Reamers are similar tools to broaches though not made in such small sizes. They have a number of spiral or straight longitudinal flutes to form the cutting edges, and are made for either hand or machine use. The purpose of the reamer is to bring to exact size a hole purposely drilled under-size, or to taper a parallel hole to receive a tapered pin. Some reamers are partly split lengthwise and have an adjusting screw fitted down the centre which is used to increase slightly, or decrease, the diameter of the reamer. Expanding reamers are also available, which have a number of cutting blades adjustable for size.