1. The triangle rulers are made of polystyrene plastic, durable, not easy to break for using a long time. They can be placed in your pencil case, or on the office desk to save space.2. Transparent color allows for a clear view of numbers and letters on the page. With the clear math ruler, you can measure an object easily.3. The measuring ruler kits can use them to measure, and draw geometric figures, etc., providing you with large convenience, suitable for a variety of applications in classrooms, offices, and homes, for artists, designers, architects, engineers and so on.