Quality Construction – Made of 216L stainless steel, our spring bars are durable and made to last. Accessorizing Made Easy – Use them with one-piece NATO straps, to be able to quickly swap between NATO and quick release straps with no tools, or to replace lost or broken spring bars. Wide Range of Sizes – Our spring bars are available in 16mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, and 24mm widths to fit a wide range of traditional and smart watches. How to Select the Size – Simply measure the space between your watch's lugs (where the strap attaches) in millimeters to determine the right size for your watch. Set of Four – Comes in a set of four spring bars.