This 6½" compass has a smooth-action, rapid adjustment feature, durable cast zinc construction, black fiberglass crown, and reinforcements. It features double knee joints for parallel leg positioning and precise drawing of large radii. It will make circles up to 12" in diameter; with the beam bar extension, draw circles up to 25" in diameter. This is a durable and economical compass for introductory level drafting or drawing. It comes packaged in a protective plastic case with spare lead.