Casio G-Shock GM-2110D-4AER Biton Advertisements from 1959 stated that

Advertisements from 1959 stated that it had been chosen by nine out of ten of the "Greats" of mountaineering for its astonishing resistance to the elements and shocks

It is part of the G-STEEL series

you’ll make a statement in all-black style

4 mm in width and a thickness of 12 mm

and a stopwatch accurate to one-hundredth of a second

Casio G-Shock GM-2110D-4AER Biton Advertisements from 1959 stated thatThe Casio G Shock GM 2110D 4AER is a vibrantly designed analog digital watch with an octagonal stainless steel case and a vibrant orange dial. It combines the bold aesthetics and rugged durability that the G Shock line is known for.