Acu-Arc adjustable curve rulers can be adjusted to any radius, from 6-3/8" to 200" (17cm to 500cm), to determine the radius of an existing curve for dimension drawings, to find center lines and center points, or determine what a curve must be to fair in existing points, or lines, on a drawing. Acu-Arc adjustable spline curves are made of incredibly flexible, shape-holding butyrate plastic that can be finger-shaped to any curve for extremely accurate drawings and layout. Adjustable curves are perfect for quilters, designers, draftsmen, artists, and more. Alvin TruFlex II flexible curves are highly versatile drafting aids made of lead-core construction. TruFlex II adjustable curves feature a raised inking edge, and graduations in both millimeters and inches. Made in the USA.