I wonder why they go rid of it. Was this shipped with every filter or was it a think you reset and put on again? Do you recall if it could tell the difference between a partial fill and full fill?
What you really want is to measure the volume through the filter, but I can't think of a way to do that cheaply and mechanical only.
It was reusable. You would turn it back to the start to reset it when you'd pull it off the top of the old filter and stick it on top of the new one.
I don't recall whether it came with the pitcher or as a bonus item included in a filter-multipack. It just counted one "tick" on a ratchet per fill/empty cycle, no attempt to measure volume or fractional fills.
What you really want is to measure the volume through the filter, but I can't think of a way to do that cheaply and mechanical only.