https://www.youtube.com/watch?v=xyK7F9_1G1o

We had these at the Abrams Building in Frankfurt where my mom worked. She was afraid to ride it at first, so the colonel she worked for demonstrated it for her. She said, "But what happens if you miss your floor?" He said, "I'll show you. I'll go all the way up and over and come back down on the other side." and while he was out of sight he did a handstand and came back down the other way upside down.

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Heater