This high quality 6" bow compass is made of rolled brass with a durable nickel-plated satin finish. It features a smooth-action, rapid adjustment feature with a sturdy push-button mechanism and center wheel for fine adjustments. Its double knee-joints allow for parallel leg positioning and use with an extension beam, ruling pen or universal adapter. It can be used to draw circles up to 14" in diameter and up to 23" in diameter with use of the included extension beam. The set also contains a universal pen adapter and two spare leads, packaged in a reusable plastic case.