Fowler High Precision Fowler's 10X Pocket Optical Comparator magnifies images which are sharp, undistorted and free of aberrations. Convenient for checking angles, thread measurements, hole sizes and more. This 10X comparator is widely used by machinists, toolmakers and inspectors in the industry. Features: Scales are photo-etched into a glass reticle which is placed in actual contact with the measured object, obtaining simultaneous enlarged images of the scale. Reticles (protected in individual plastic cases) are easily interchanged by a screw-in mount. Measures radii, diameters, angles, hole sizes, pitch and thicknesses. With the illuminator attachment, the comparator converts into a self-contained illuminated measuring magnifier.