General description Made of premium acrylic sheet, these 5X Clear Marine Parallel Ruler Scales are designed for drawing lines bearing the course, degree, or quantity of the line. They are an essential accessory for drawing and measuring nautical charts, providing accuracy and ease of use. Technical specifications Material: Acrylic fiber Length: 450MM Measurement allowed error: +/- 1-3 cm Usage Designed for drawing lines in nautical charts. Two hands can hold each ruler, moving them alternately in parallel for easy drawing. Sturdy construction provides the right amount of tension to draw lines parallel to reference points. Other information Package Contents: 5 pcs parallel ruler Note: Light reflection and different displays may cause the color of the item to differ slightly from the real thing.