High quality material: Made of aluminum alloy with anodic oxidation treatment, it is durable and rust-proof. High hardness, anti-rust, non-corrosive, permanent use. Perfect 90 corners: This precise clamping square is designed to be fixed on boxes, frames, etc. to help you square during gluing. This right angle positioner has two extra notches. True right angle for interior and exterior squares. Base and fold for straightness and parallelism. How to use: Place a square in the corner of the two pieces you need to square and secure with a set of pliers. Metric and inch graduations. Accurate calibration, easy operation, will not easily damage fragile cutting edges.Available in 12cm, and comes in a set of two. Professional design: designed to be attached to boxes, photo frames, shelving cabinets and for exterior corners, etc., to help square when gluing. Beveled edges, easy to handle and do not damage fragile cutting edges. Wide application: you will have exactly what you need to perfectly create boxes, drawers, cabinets, frames, furniture, etc. Some carpenters even find it useful to integrate them into their templates and fixtures. Satisfaction - Great usefulness - Efficiency square.