With Armstrong's watch left in the lunar module as a backup timer, Aldrin strapped his Speedmaster over his suit and became the first person to wear a watch on the Moon. It went missing in 1971 on its way to the Smithsonian; the ref. 3590.50.00 he bought in the 1990s as a replacement sold at Sotheby's in 2026.
20 mm
Most common strap size on this line: 20 mmCases 42 to 43 mm
Source: London Review of Books, Smithsonian Magazine, Esquire UK