OK, this is a hard one so I’ll give you a 2 clues.
Clue # 1 : this is on something that was very common in the old days
Clue # 2 : I don’t know anyone else who has one of these in their house today
Can you guess what it is without investigating the brand name on it?
Looks like the adjuster for the ringer on an old washing machine. Remember the name from Grandma Wurzer
Maybe the washboard you have, the handle is worn a lot in the middle