Internal Program Version: pv v1.8.9 (The man files)

PV ("Pipe Viewer") is a tool for monitoring the progress of data through a
pipeline. It can be inserted into any normal pipeline between two processes
to give a visual indication of how quickly data is passing through, how long
it has taken, how near to completion it is, and an estimate of how long it
will be until completion.

https://www.ivarch.com/programs/pv.shtml