Scratch-resistant probe head - The top of the probe head is smooth, not easy to wear the lens (with probe protection cover). Stainless steel thread - Fine workmanship, comfortable feel, non-slip and not easy to fall. Scale and pointer - Precisely measure the curvature of the lens, anti-shake pointer, clear data display. For use with both glass and plastic lenses. Quickly identify and check base curve. Precision scale is uncrowded and easy to read. Note: Installation guide not included,Please check as much as possible to make sure the item is what you need. Tips:The product may be updated constantly, Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use. Colour:As Shown Material:stainless steel Package Contents: 1 * Clock Radian Apparatus Gauge Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.