This product contains 20 x 11.5mm Butyl Patch in a pack of 10 and can be used either as a spare part or replacement. This 10 pack of Rhino-Rack Butyl Patch Seal can be used either as a spare part or replacement. The Butyl Seal is designed to be used with a range of Rhino-Rack Roof Racks and will prevent water from entering through your roof rack. The Butyl Patch are a must-have for any vehicle. They are used to seal off any minor cracks, holes or weak points in your vehicle.They can be used as a replacement for damaged ones or left as spares for future use. This product is suitable for use on most vehicles carrying roofs. Butyl patch seal is a right and easy solution for minor damage on your roof rack system. Its butyl material keeps the boat sealed, not letting any water or moisture to get into your car.