Material: The edgeless clasp pop-ups are made of metal, which is strong and durable. The iron material provides sufficient strength and stability to allow the backing to be firmly fixed to the frame. Size: Clip are available in a Medium size, 35 mm long and 13 mm wide. This size is designed to fit common picture frame sizes, ensuring that the poppers fit snugly into the back plate and frame. Function: The function of the buckle spring is to fix the back panel of the photo frame so that it fits the photo frame tightly to protect the photo or artwork. They provide a simple yet effective solution, making backplates easier to install and remove. Installation: Using these edgeless clasp pop-ups is very easy. You simply insert the tabs between the edge of the frame and the back plate and press down to fasten. This design makes the installation and removal process easier and faster. Quantity: You will receive 20 snap fasteners for the back of the frame,are used to secure the back plate of the frame and ensure that the back plate is securely fastened to the frame.