This magnifier was rated second overall in the independent study by the Science & Practices Committee. It was rated highest in field-of-view and viewing distance comfort. This glass resembles the M-H Classification Magnifier above, except that it is larger. The thumbscrew allows the lens housing to move up and down the shaft to focus perfectly for your eyes. The base, shaft and lens housing are metal. The view is clear and focused across the entire distortion-free, flat-field lens. 3x magnification allows for comfortable viewing and the wide 2.4375" diameter opening at the base allows for easy insertion of a ridge counter. An optional threaded crosshair reticle disc is also available for this magnifier.