Wall Luminaires,Outdoor Sconces,Wall Sconce,Wall Lamp Light Ningbo Royalux Lighting Co., Ltd. , https://www.royaluxlite.com Tool microscopes generally have a circular contour lens, referred to as the R lens. It is a concentric circle and an arc engraved line marked with a series of different radius values. China's JX7, J19jA tool microscope R lens engraved with a concentric circle of 0.1 ~ 1.5mm and a standard circular arc of 0.1 ~ 50mm or 0.1 ~ 100mm. The R lens is mainly used to quickly solve the problem of on-site measurement of workpieces during production. Use the R lens to measure the arc radius, it must be the workpiece nominal arc radius is equal to the R lens standard arc engraving calibration value