It was supposed to come to the market around the time of Nokia-Microsoft deal but was cancelled by Microsoft after the deal. We are talking about Microsoft aka Nokia Moonraker, some images of which have been posted on Tumbler and were discovered by Evleaks today. A Smartwatch that was developed by Nokia to complement its Lumia range and you can see the very close relation with the colorful Lumia design in below images. The OS may have been Windows based though it is not entirely clear.
Nothing to look forward as this has been cancelled and Nokia has already killed its own plans of an Android-based Smartwatch in near future that could have arrived from HERE. As per Evleaks the model number for this device was LS-50
.@evleaks FWIW, the model number for this is/was LS-50.
— Evan Blass (@evleaks) June 12, 2015