The Starrett extension dividers are exceptionally rigid although light in weight and easy to handle. The head is made of forged steel. The hardened points are well shaped and bent slightly so they can be rotated and brought closer together if desired. The sturdy construction of the joint, combined with the quadrant that projects through the legs and is frictionally locked by a knurled clamp nut, eliminates side deflection of the legs. A quadrant adjusting nut permits fine-adjustments for close measurements. A check nut located between the legs firmly locks the legs after proper adjustment has been made. This feature prevents the legs from moving in and out with the grain on wood when scribing, or sliding off rough spots when scribing on metal.