Dia19mm 20mm 24mm Eyepiece Graticule, Measuring Glass Micrometer For Microscopes microscope stage calibration slideFeatures:optical glass.High-quality and Reticle-graticule in 0.01mm.There are three sizes on offer: 19mm 20mm and 24mm. Please choose the right size for your microscope.Please choose the right size for your microscope.Specifications:Material:GlassDiameter:19mm/0.75'',20mm/0.79'',24mm/0.94''Package Includes:1x Oculars MicrometerNote:Please allow 1mm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item.