A throwback to the past.
I assume that is a handheld TC. The internal circuitry of that handheld digital gadget would have been black magic in 1960. It would have taken a computer the size of a small file cabinet, or the Apollo landing computer. The digital display would have been Nixie Tubes. Which, I am amazed to discover, you can still buy:
https://vetco.net/products/in-…git-0-to-9-vertical-mount
Marvelous things, but not small. Complicated, and hot. You cannot drive them with a handheld battery.