Big Time is one of the participating shops where retired SAF personnel can make purchases with their farewell vouchers. I often see these retired soldiers come in and purchase watches for themselves and the family members.
Here is a set of land, sea and air watches that were produced under contract for this purpose.
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Yeoman's Weblog 
do you sell used watches ?
No
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Where can get the navy design watch
It’s available at Big Time, 483 Sims Avenue.