Paylak UNIKEY-1O Odd Sizes 5 Prong Universal Clock Key for Winding Clocks Universal clock key Used to wind most clocks Odd sizes: 5 prong Brass key Sizes: 3mm 1/8 in (3), 3.5mm 9/64 in (5), 4mm 5/32 in (7), 4.5mm (9), and 5mm 13/64 in (11)