Easy to operate, users only need to adjust the focal length by holding the lens tube, which is and fast; Suitable for stage performances, theatrical performances, and other scene, it can better observe stage and enhances the viewing for use in theaters, live performances, and other event where you want to enjoy a great viewing The 30mm lens with wideband coating technology provides a clear and wide field of view. Specifications: 4X30; Magnification Objective diameter:30mm;