Lockheed navigational computer circular slide rule key chain 1960 USA

This very small round slide rule is actually a key chain. It is marked “Lockheed California” and was produced by the Pacific Products Company also from California / USA. These were probably available to pilots for actual use since these are able to do some quick aviation calculation including Ground Speed. It is completely made of metal and in unused condition. It also comes with the original tiny box and manual. The box did suffer from storage since it is missing a small piece of the bottom. It measures only 4 cm or 1 3/4 inches in diameter which makes this the smalles circular slide rule I have seen yet. Check the attached video on how to work your vintage man tool : slide rule operation instructions!