These are highly polished solid metal flip over tops. They have a chrome like finish and are excellently machined. Simply spin it as normal and watch it suddenly flip over and then continue to spin upside-down.

Flip over tops (often known as a The Tippe Top) were originally invented in 1950 by the Danish engineer Werner Ostberg. His inspiration can from a visit to South America where he had seen local people playing with a small, round fruit. When they turned it by the stalk like an old-fashioned spinning top, it would spin for a second and then invert and spin on the stalk.
However some credit should be given to Helene Sperl who in 1891 patented a "Wendekreisel" in Germany. However the patent ran out and it was never mass produced.

The tops are 29mm in diameter ( 1.14 inches )
and about 36mm tall (1.41 inches )