Used Topaz 24" HD Desktop Video Magnifier: It has been checked and works well.

  Controls are:

•  Bigger and smaller Magnification-(up to 45X)
• Color selects options. (Black and White, White and Black, and more)
• Automatic Focus
• Writing under the machine. (Checks and letters)
• See pictures in full-color mode.
• Brightness Control
• Please call 1-800-871-870 with any questions regarding this reading machine.