5 Sided Pocket Watch. Key For Winding Watch Mainsprings. This is a new 5 sided pocket watch key. Great for winding watch mainsprings. Has sizes 3, 5, 7, 9 and 11. The hole sizes are 1.65, 1.50, 1.30, 1.15 and 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.