High Quality] This architect ruler is made of anodized aluminum alloy, solid and sturdy. Designed for maximum durability, this 3 sided engineering ruler is perfect for long-time use [Laser-etched Scale] The metric scale ruler with durable laser cut metric prints for accuracy. They will not wipe or scratch off ever [Metric Scales]3 sides with 6 scales: 1:20, 1:25, 1:50,etc. Ideal for blueprint, professional applications, architecture, civil engineering, drafting and technical illustration(Notice: Make sure it is what you want before placing the order) [Precise Scale]The black scale ruler is professional grade with supreme accuracy, suitable for engineers, professors, hobbyists, manufacturers [Safe Tool]Our tri-scale ruler was created with your safety in mind. Chamfer edges design, comes with a protective bag, no more accidental pokes, scratches and cuts