A false square is an adjustable measuring tool used to transfer and measure irregular or non-perpendicular angles. It consists of two arms joined by a screw or clamping mechanism at one end, allowing the angle between them to be varied as required.
Unlike the fixed square, the false square does not have a predetermined angle, but is manually adjusted to the required angle. This makes it ideal for copying specific angles from one part to another, or for working on surfaces with custom inclinations.