Material: Made of durable metal, they are sturdy and resistant to corrosion and rust. Grommet installation tool to reinforce holes and prevent tears. Convenient: These durable grommets are easy to use, perfect for canvas, tarps, tents, awnings, belts, clothing, backpacks, etc. hand, bags and other items. Easy storage: All eyelets and tools are contained in a transparent storage box. Makes it easy to find matching components. Grommet Dimensions: Hole Inner Diameter: 12mm, Outer Diameter: 21mm, Height: 6mm. Features: Hole drill first punch a hole in leather, leather straps or clothing with the punch tool, then use the hammer to drive the eyelets into place. This is a set of handy tools for adding embellishments to your crafts.