Optical glass reticle insert for eyepieces and small optical instruments. Available in two diameters for compatibility with common eyepiece sizes. Key features Material: Optical Glass for clear imaging and reliable durability. Sizes: Diameter 20 mm or Diameter 24 mm options to fit different eyepiece mounts. Scale: DIV=0.1 with Grid Cross Scale Reticle for fine, repeatable measurement and positioning. Construction: Precisionetched grid on glass for stable performance and long service life. Why choose this reticle Enables precise measurement and alignment inside microscopes, telescopes, and other optical systems. Durable optical glass maintains clarity and scale accuracy over extended use. Two diameter options increase compatibility with a range of eyepieces and adapters. Typical applications Microscopy: Measuring and documenting specimen dimensions when calibrated to magnification. Inspection and metrology: Visual alignment and size checking for small parts, circuits, and components. Astronomy and imaging: Framing, centering, and alignment tasks for eyepiecelevel adjustments and targeting. Important notes Transition: 1cm=10mm=0.39inch. Due to manual measurement, allow an error of 03mm. Please confirm tolerance is acceptable before . Colour shown in product images may differ from the actual item due to monitor variations. Compatibility and use tips Choose the diameter that matches the eyepiece or insert mount of your optical device. Calibrate the reticle under known magnification to convert DIV=0.1 scale units into real world measurements for your setup. Handle glass surfaces carefully and clean with appropriate optical cleaning materials to preserve the etched scale and appearance.