These Clock Winding & Letting Down Release Tools are metal tools designed for winding and letting down the mainspring of clocks. 5 tools each with different sizes on each end. We have 2,3,4,5,6,8,10,11,12 & 14 stamped on the ends. This is not mm but as the number increases so does the size. Each measures 9cm Excellent condition. despatched via Royal Mail or Evri.