The Cose Metal Buckle with Rectangular Slider, 20mm in diameter and made of copper, is a rectangular frame-shaped metal buckle used to adjust the length of straps and belts without a fastening function, only a sliding mechanism. The copper finish provides a warm and distinctive touch, making it a popular choice in more vintage or handcrafted leather goods. It is an essential accessory for those who make bags, backpacks, and adjustable straps, offering a more robust finish than conventional plastic.