Hard-to-find winding keys for clocks with square mainspring winding shafts * Two keys cover 10 most-common sizes in odd & even-numbered sizes * Even: 2 (2.8mm), 4 (3.2mm), 6 (3.6mm), 8 (4.0mm) & 10 (5.0mm) * Odd: 3 (3.0mm), 5 (3.4mm), 7 (3.8mm), 9 (4.2mm) & 11 (5.4mm) * Save time & money over trying to find right single-size key; 3" diameter keys, all brass