Fowler 52-664-009-0, 10x Pocket Optical Comparator Set with 9 Recticles

Optical comparator with 10X magnification and set of nine reticles for measuring line thickness, screw threads, angles, radii, circles, degrees, and length
Glass lens provides high-resolution images
Scales are photo-etched onto a glass reticle for accuracy and distortion-free viewing
Set of nine reticles includes thickness and hole reticle; line thickness reticle; circle, square, and angle reticle; metric screw thread reticle; inch screw thread reticle; angle reticle; inch/metric linear scale reticle; metric reticle; and a circle, angle, and concentric circle reticle
A dioptric number and a magnification number are not the same thing. Diopter strength represents a specific magnification power (X). For example, a 5-diopter provides 2.5X magnification (at a distance of 8″)