New Old Stock

New Old Stock, or NOS for short, refers to retail items or products that are still technically brand new, but have never been sold for long periods of time. This is commonly due to newer and/or upgraded versions of the same product being released, rendering the older models obsolete. Thus, this makes them old stock. But because they're still technically brand new, unused, unsold products, they are termed "new old stock".

New old stock units are typically sold at a greatly reduced price, since most of the focus and attention is put onto selling the current models. Retailers and vendors will usually have various quantities of new old stock left over from the previous product generation cycle, and will sell them at reduced prices to clear them out in order to accommodate for newer models.

John: Whoa, got yourself a new tennis racket huh?
Brian: Yep, only cost $60.

John: Wow that's a steal! How'd you get it for so cheap?
Brian: New old stock. This particular racket model came out in 2014, so it's been replaced numerous times already with fancy newer models. I figured hey, it's still technically brand new anyway, and tennis racket technology hasn't really changed over the past few years, so why the heck not?