The Combination Angle is a multi-purpose measuring and drawing tool based on a steel ruler with a guide groove and a removable, sliding head. The head can be moved freely along the ruler and locked in any position by means of a locking screw. The standard angle head has one side ground at exactly 90° and the other at 45° to the ruler. This allows the tool to be used as a precision miter gauge for checking and scribing right angles as well as a miter gauge for 45° angles. The head often includes a small spirit level or spirit level and an integrated drawing needle. The term 'combination' refers to the ability to combine several functions into one tool. The sliding function of the head also allows it to be used as a depth or height gauge. The possibility of changing the head further extends its functionality; for example, there are protractor heads for setting arbitrary angles or centering heads for finding the center of round objects.