These are hooks for the laces of lace-up boots, such as work boots and hiking boots (trekking shoes). Attaching them to sneakers might make them easier to put on and take off. Total Length: Approximately 8.2mm Head Diameter: Approximately 7.5mm U-shaped Inner Diameter: Approximately 3mm Foot Diameter: Approximately 9.5mm Foot Length: Approximately 6mm Leather Thickness: Approximately 4mm Body Material: Brass Washer Material: Iron Quantity: 12 sets