The first picture shows a watch balance on a watchmaker poising tool, a tool used to statically determine the evenness of watch balance wheel weight distribution with its roller table and jewel installed. It is important that the smooth ruby jaws of the tool be perfectly clean and level (second picture showing leveling.) Today, some watchmakers that I respect but disagree with, claim there is no use for this tool, they have gotten rid of them, and instead they rely solely on a technique called dynamic poising to measure, compensate and equalize the balance and its hairspring together while in the watch using timing machine measurements. I believe in dynamic poising as a technique but couldn’t disagree more relative the importance of the tool shown, used in static poising. The vintage watches I service have been handled so many times—so many things done to them by past watchmakers— that you must go back to first principles and statically analyze and adjust extreme imbalances as-required before dynamic posing. Past watchmakers errors, balance staff changes, hairspring issues and changes, and roller jewel/table changes and changes in orientation, and damage can all impact a watch and I do not like to adjust anything this sensitive until I collect all the facts. The last thing I want to do is adjust a watch to compensate around some attribute that is largely incorrect. The poising tool is one of the last tools I would give-up for vintage watch servicing.