Dimensional gages and instruments provide quantitative measurements of dimensional and form attributes such as wall thickness, depth, height, length, inner diameter (ID), outer diameter (OD), taper and bore. There are many types of dimensional gages and instruments. Gage blocks or master gages are used to calibrate, check, or set variable or fixed limit gages. Gage systems or stations are large, complex units that are typically available in bench top or floor mounted configurations. Go/no-go, functional, and attribute gages are precision tools for comparative gaging based on fixed limits. Indicators and comparators include a precision spindle whose linear movements are amplified and displayed on a dial or digital display. Dimensional gages and instruments include specialized devices that measure thickness, thread size, pitch, serration, and other parameters. Height gages include micrometer, laser micrometer, and micrometer head gages.