Features: 1.Made of 2Cr13 stainless steel, polishing, hardness HRC over 30. 2.Metric scale, 180 ° rotation, can be measured in different angles. 3.Screw nut fix the ruler. 4.0-180 °Surface use laser engraving easy read, durable in use and precise measurement. 5.Stainless steel ruler edge have been polished smooth to protect hand use