2PC Universal Brass Clock Winding Key - Even Sizes 4 6 8 10 - Odd Sizes 3 5 7 9 Even Numbers:Sizes: 2.75mm 7/64 in (2), 3.25mm 1/8 in (4), 3.75mm 0.14 in (6), 4.25mm 11/64 in (8) Odd Numbers: Sizes: 3mm 1/8 in (3), 3.5mm 9/64 in (5), 4mm 5/32 in (7), 4.5mm (9) Brass Body Used for Jacobs Chucks, Flexible Shaft Grinders, Power Tools etc. Including: 2 pieces