Alvin TruFlex flexible curves are easily shaped to hold most any curve. These highly versatile drafting aids are made of aluminum-core construction. TruFlex adjustable curves feature a raised inking edges for pen and marker use. Flat edges on both sides for pencil drawing. Graduations in both millimeters and inches. Metric graduations are marked in red, inches in black for easy identification on white scale backgrounds. Lead and phthalate-free.