This is a factory-style string hook, useful when installing strings or when leveling strings for voicing.
The tool has a wide but thin tip, narrow enough to drop between the strings of a unison without turning the tool, but wide enough to give strength for pulling up on the wire.
You can merely drop it down between the strings and hook the wire in one easy motion for string leveling.
Special Note: This hook is designed for string leveling and string voicing work. It is not intended to serve as a coil lifting hook during restringing, as the tip could wear and break prematurely.