Regicocraft Angle Gauge Ruler #92911Made from durable hardened plastic, this miter saw protractor is superior and stronger than traditional plastic angle finder. It is resistant to scratch and very durable. The back o ring mechanism swivels during operation and ensures smooth and precise read on inside outside and all kinds of angles on woodworking, carpentry trimming or DIY jobs. Single cut use outer scale to miter saw settings for fitting a single piece to angle. Miter cut use inner