The Cyr wheel

YouTube link.

The Cyr wheel (also known as the roue Cyr, mono wheel, or simple wheel) is an acrobatic device popularized in the early 21st century.

There are records of people using a similar apparatus as sports equipment during the 19th[citation needed] and 20th centuries. The cyr wheel was further popularized as a circus skill by numerous acrobats and circus artists during the 1990s and later by Daniel Cyr in 2003, who presented the first cyr wheel circus act at the 2003 Festival Mondial du Cirque de Demain in Paris...

 Cyr wheels are typically made of aluminum tubing. Usually a 1.5” diameter tubing with 1/8” sidewall 6061 aluminum is used. Generally they are made in 3 or 5 individual pieces, and connect with inserts. The inserts can be made out of solid aluminum or steel (either tubing or solid). They are then painted, and covered with a plastic PVC covering to add friction, and protect the metal. Smaller wheels spin faster, work better for smaller spaces, and make "no hand" tricks easier than larger wheels. Larger wheels are more graceful and there is more room for suspensions.

In the video a young man documents his first 30 days using the wheel.  Via Neatorama.