Vintage Antique GRADY TECHNOMETER X-Ray Technic Calculator— VERY RARE!

This is an antique very rare X-ray exposure calculator, often referred to as a "technometer", designed by Grady. It is a cylindrical slide rule designed to help X-ray technicians determine the correct exposure settings (kilovolts (kVp) and milliamperes (mA)) for various body parts and types of X-ray examinations. The device was manufactured by Sukumlyn & McConnell in Los Angeles, California. I’m not sure when this was manufactured, perhaps in the 1930s, but it could be older. It comes in original wood box, which has some damage at closure as shown. The device itself is in good condition, but I do see a small crack at one end housing as shown. Otherwise very good. Glass sheathing is intact and not cracked.