Horolovar mainspring let down tools. Mainspring let down tools are used to safely unwind your clock's powerful mainspring, so that you may disassemble the movement for proper cleaning and lubrication without injuring yourself and causing extensive damage to the movement. These tools are designed to fit over your clock's key, and work for almost all keys currently on the market. There are two sizes to handle both smaller and larger clock keys. These tools are built to last, with solid cherry hardwood handles, and thick, high quality steel.  For more detailed instructions on how to let down your clock's mainspring, see our website at www.thehorolovarcompany.com.