Anodic oxidation, it is durable and rustproof. High hardness, rustproof, non-corrosive, durable use. Perfect 90° Corners: This precise clamp square is designed for attaching to boxes, frames, etc. to help you align when gluing. This angle positioner has two additional notches. True right angle for inside and outside squares. Base and folded for straightness and parallelism. Application: Place a square in the corner of the two pieces you want to straighten and fasten it with pliers. Metric and inch graduation. Accurate calibration, easy to use, fragile cutting edges are not easily damaged. Available in 12 cm and set of 2. Professional Design: Attach to boxes, picture frames, shelf cabinets and for outside corners, etc. to help you align when gluing. Beveled edges, easy to handle and will not damage the delicate cutting edges. Wide Application: You have exactly what you need to perfectly make boxes, drawers, cabinets, frames, furniture, etc. Some carpenters even find it useful to