The BelOMO 20x 17.5mm (0.50'') Quadruplet Loupe Magnifier has a viewing area of 0.28" (7mm), much larger than the Bausch & Lomb Hastings Triplet Magnifier. The 4 elements making up this quadruplet provide a bright, and clear view. The 20x power magnification provides the strongest magnification recommended in a hand held magnifier. While a 20x power magnifier provides lots of magnification you'll find depth of field (that amount of vertical relief that appears in focus) small. The housing and cover are coated with a matte black finish and assembled using flat head screws. Belarusian Optical and Mechanical Association (BelOMA), makers of sights for guided weaponry, camera lenses, and other optical components manufactures these loupes. The high quality optical lens of each loupe is tested and certified, just like a camera lens.