Inside diameter gauges perform direct or indirect measurements on holes or bores for precise measurements of their inside diameter anywhere between the surface and the base. Bore gauges have dial, digital, and non-reading styles that perform direct or indirect measurements of inside diameters using two- or three-point contact designs or measuring rods with anvils. Taper slot gauges are solid pieces of metal that taper to a point and have graduations along the sides to give a quick reference reading. Telescoping gauges are inserted into bore holes and the telescoping arm or arms are expanded or engaged in a hole. When withdrawn, a regular outside micrometer is used to measure the locked length of the gauge. Small hole gauges are expanded in small holes for measurement, while large diameter gauges have specialized construction for the direct reading of very large bore diameters. Taper slot gauges taper to a point and have graduations along the sides to give a quick reference reading.