"Very heavy metal object found in a garden. Top plate in the second picture can spin around. Rest of the object is so rusted nothing can move."
A: "It’s an old ceiling support from a coal mine. This is in the “Titan” style and was introduced in 1948, just after the second world war. It was used in all the state mines and quickly became the standard. It’s one of the last variants before hydraulic supports were used."
For you younger guys. Dating was much more fun before pantyhose.
It is used to keep the pistons from the disk brake caliper separated when the wheel is removed in case the brake lever is pushed accidentally.
It's from Adafruit, the company famous for their DD8008S and attempted takeover of Apple... so everything else is obvious.