A professional who assembles, inspects, and adjusts watch hairspring and balance assemblies, using watchmaker's tools. Responsibilities include:

• Attaches hairspring to collet and stud, and assembles parts of hairspring and balance, using punch, staking tool, tweezers, and other watchmaker's tools.
• Overcoils spring, and trues spring.
• Poises balance wheel.
• Locates vibrating point.
• Inspects and adjusts hairspring and balance assembly.