"A circular metal object with a hole in the center. Symbols are carved in its side."
Cylinder is an event item in Resident Evil.
The Cylinder is to be combined with the shaft before rearranging its "I II III IV" label to the right pattern. Once done, it can be placed back on the elevator panel at the generator room to get the elevator working again.
The Cylinder is found inside a small shutter at the Underground Statue Room of the Courtyard. One statue out of place is needed to be moved back to the right place in order for the shutter to open.