NOS, or New Old Stock, refers to items that are old but have never been used or sold at retail. In the realm of watchmaking and horology, NOS typically describes watches, watch parts, or accessories that were manufactured in the past but have remained unsold and unused, often stored in their original packaging. These items are considered highly desirable by collectors and enthusiasts due to their pristine condition and historical value.

NOS watches offer a unique opportunity to own a timepiece that is essentially brand new, despite being produced years or even decades ago. This can include vintage models that are no longer in production, providing a glimpse into the design and craftsmanship of a bygone era. The appeal of NOS items lies in their authenticity and originality, as they have not been altered or refurbished, preserving the manufacturer's original specifications and details.

In addition to complete watches, NOS can also refer to individual components such as dials, hands, or movements, which are invaluable for restoration projects. Collectors often seek NOS parts to maintain the originality of vintage watches, ensuring that repairs or restorations do not compromise the watch's historical integrity.