Feature:This tool is for regulating/timing for watches. Many for watch movements have tiny screws on the balance wheel which turn to apply tension to the hairspring.This tool allows the precise rotation of those screws with its specially designed end which grips and rotates the screws. Lines inside the plastic housing indicate and measure the amount of rotation.This is a professional tool for the watchmaker who services for watches.Fit for 2130, 3035, 3055, 3135, 3155 or similar.Full Instructions:Hold the balance rim with tweezers. Fit the end of the key onto the nut.Turn the key in the direction necessary for the correction.In the event of a tight nut, correct the misreading caused by the torsion at the end of the key. It is essential that the adjustment of a pair of for Microstella nuts, short or long, be identical, so as not to modify the balance wheel poising.Package includes:1* Watch Balance Regulating Key Wrench Tool