Utilizes a three-element, two group achromatic optical glass construction. Bright, sharp, loupe with a 360 degree clear acrylic base to admit light from all directions. Inner Diameter of the Eye Piece 3/4" Outer diameter of the base 1 3/8" Magnification 15X Focal Length: 21.8mm Field of View 19mm Size 36 x 34.5 mm Net Weight 18.4 g