These eliminate the need to make paracord bracelets the exact size, as the shackle allows the bracelet to be made smaller or larger. Each unit consists of a D-Shaped stainless steel shackle and a contoured multi-hole bar. The bar has 4 holes. Three of the holes allow bracelets (or whatever else they"re utilized on) to be adjusted in length. Due to its complex shape, the bar is made of Corrosion-Resistant Zinc Alloy. Shackles are classified by the diameter of the metal in the bow. The thicker the material, the stronger the shackle. The D-Shaped shackle is more narrow than a bow or anchor shackle. The smaller loop is designed to take high loads primarily in line. While these shackles can have other uses, they"re great for making stylish paracord bracelets. Steel Shackles are much more durable than plastic buckles, and along with paracord, can be quite useful in a survival situation.