This specific example is a ref 145.022, houses a cal. 861 movement and was purchased in 1971 by an US Army helicopter pilot, who used the watch during his tour of Vietnam. This watch originally came with the ref 1171 bracelet.
(1) Apollo Lunar Surface Journal: Omega Speedmaster Watches (http://www.hq.nasa.gov/alsj/omega.html)
The Speedmaster Professional, AKA the “Moon Watch”, is arguably the most historically significant watch made by Omega. Dozens of pages and articles have be written about how it was chosen to be the first watch to be worn on the moon. This topic has also yielded dozens of crackpot conspiracy discussions, but at the end of the day the facts are that NASA was looking for a watch to be used during extravehicular activity (EVA) and selected a few watches to be tested under extreme conditions. At the end, the Speedmaster Professional was selected for the task and was the first watch to be worn on the moon (1).
Speedmaster Professional 145.022