The Conic EL-601, introduced in 1978 and made in Hong Kong, sports a bright red LED (Light Emitting Diode) screen. The LEDs are positioned behind convex lenses that enlarge them to the benefit of the user.
It's 118mm high by 72mm wide, and tapering from 24 to 14mm thick. It takes a big 9 volt battery, and turns on by a sliding button on the left side of the device.
Interesting about this particular calculator is that it was used as a piece of advertising by the now-defunct American A.B. Dick Company: the words "A.B. Dick daagt drukkers uit tot rekenen..." are printed in white across the top of the device. Translated from Dutch, it means "A.B. Dick challenges printers to calculate" (at least I tried). I imagine that with big orders, the company gave out these calculators, which were quite the commodity in the seventies.
The buttons press down with a satisfying "click", assuring the user that something is definitely happening. Incompetent users are punished for their calculating errors by the screen rapidly flashing its letters at them until they reboot the device. A chunky 9 volt battery is required.
A device for angry, burly men.