It is a curved ruler used by tailors. It is used mainly in the sewing room. Keep away from children and under age. It is versatile. It can be used for all levels of learners. It is made of plastic. It can also serve the purpose of an armhole curve. It is one of the most essential tools for a  pattern drafter. It is used in drawing curves around a pattern. I.e. necklines, armholes, etc. It can also be used in drawing curved lines on a pattern. It can also be used for contouring. It can also serve as a ruler and A tee square. It is made from acrylic. It is resistant to water. It is a universal tool. It can also be used to draw straight lines.