A Combination Square is a versatile measuring tool used in woodworking, metalworking, and other trades that require precision measurements. It consists of a ruler-like body with a handle, a blade that slides along the body, and a head that can be rotated and locked in place at different angles.

The blade has graduations marked on it, usually in both metric and imperial units, allowing for precise measurements of length and angle. The head of the square can be adjusted to 90 degrees, 45 degrees, or any other angle within its range, making it ideal for tasks that require precise angles.