![Ball Tipped Lens Clock #2068BT](http://westernoptical.com/cdn/shop/products/measuring-2068BT_{width}x.jpg?v=1547934839)
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Curves Worth Knowing.
The higher the patient’s Rx, the more important the base curve be specified in the Rx. A dramatic change in the curvature can cause the patient problems. This clock provides precise curvature measurements on glass and plastic lenses. Rounded steel tips prevent scratched lenses. +\-20 diopters. Self-adjustable re-calibration.