12 American Clock Keys Two 5 Pronged Winding Tools 2 Size 5 Clock Keys. This is a new set of 2 size 5 clock keys. You receive: One size 5 clock key with a 1.75 mm hole and a 3.50 mm hole. One size 5 clock key with a 1.95 mm hole and a 3.50 mm hole. New 5 Sided Clock Key. This is a new 5 sided clock key. The sizes are: Size 3, 3.00 mm. Size 5, 3.50 mm. Size 7, 4.00 mm. Size 9, 4.50 mm. Size 11, 5.00 mm 5 Sided Pocket Watch. Key For Winding Watch Mainsprings. This is a new 5 sided pocket watch key. Great for winding watch mainsprings. The sizes are: Size 3, 1.65 mm. Size 5, 1.50 mm. Size 7, 1.30 mm. Size 9, 1.15 mm. Size 11, 1.00 mm. We work hard to update our descriptions and pictures of our merchandise. As part of a process of ongoing innovation by our suppliers, newer versions of the item shown may be shipped before we are able to complete an update. As a result there may be a slight variation in color and design.