The 6.5" small Gammon Reel is used to suspend a plumb bob under a surveying instrument. It can also be used to suspend a plumb bob while providing a target to accurately position with a surveying instrument.
Use the 6.5' small Gammon reel as an aid to set up and deploy a clean, accurate plumb. Slip the reel into your palm and draw the bob to the desired position and stop with finger pressure. The steel clock spring zips the string back into the case.