1. The surface of our slides are tipically flat and optically clear. 2. We have 3 types of edges to match the various usage: A. Cut (unground) edges B. Smooth and ground edges with 90 degree shapes. C. Smooth and ground edges with 90 degree shapes and with sprecisely clipped corners. 3. Our standard slides have 22 or 20mm frosted at one end on single side or both sides for easy marking. 4. Our concave slides have one or two circular recesses which have a depth of approx. 0.6- 0.8mm and a diameter of approx. 15-18mm. They are excellent for viewing and using. 5. We have full regular types. And customer sizes are available