Alvin Adjustable Curves

Made of incredibly flexible, shape-holding butyrate plastic that can be finger-shaped to any curve for extremely accurate drawings. One edge is flat to surface for pencil, and the other side has a bead for ruling pen. Still manufactured by hand, these curves have been used by architects, engineers, chiropractors, designers, draftsmen, artists, woodworkers, metal workers, surveyors, carpet installers, and law enforcement for 45 years.