Keystone Mainspring Winder. If you're serious enough about clock repair to invest in a mainspring winder, Keystone is the one you want to buy. Made in America, the quality is second to none, and it has everything you need to quickly and efficiently deal with loop and hole end mainsprings. The winder comes complete with a clamp to hold barrels while removing or inserting mainsprings, a nest of 11 spring retainers, anchor pins for loop and hole end mainsprings, a hex wrench, a set of 5 universal arbors, 4 mounting screws, and detailed instructions for use.

The advantages of a Keystone mainspring winder:

Simple to use -  The square chuck grips the square end of the winding arbor, and tightens by hand. No wrenches or seat screws to adjust, and no damage to the arbor. The handle is free to rotate in either direction. When locking is desired, just slide the lock back. You know it's absolutely secure. No ratchet to reverse or wear out.

Versatile - The chuck ranges from 2mm to 5mm (#000 to #13 American key size). The removable vise bar allows mounting in a vise, on your work bench, or on the wall. Left or right hand operation, horizontal or vertical, portable or permanent. The winder winds both loop end and hole end springs of all sizes - It even winds loop end springs in the movement when the click or ratchet is shot, so you can clamp the spring for disassembly of the movement.

Fast - It winds, unwinds, inserts, and removes mainsprings smoothly and easily. All adjustments, clamping, and sliding is done quickly by hand with no hooks, ratchets, wrenches, or screwdrivers.

Safe - There is no need to wear protective gloves. The clamp holds the barrel securely while removing or inserting mainsprings. It's resilient rubber surfaces grip firmly without distorting or scratching the brass barrel. The clamp adjusts easily to all barrel sizes, and anchors firmly to the winder.

Complete - The winder includes a nest of 11 spring retainers in sizes 1" to 2 3/4" for nearly any barrel size, detailed instructions for use, a parts list, and suggestions.