What is the width of the Zinc Moss Control 50 ft. Roll with Nails strip?

The Zinc Moss Control roll is 4 inches wide X 50 feet length

The Zinc Moss Control roll is 4" wide X 50' length and is a roof moss, algae and fungus inhibitor. Apply in strips to old or new roofs. Works with any wood or composition roof and lasts for many years. Easy to install, safe for roofing shingles and an ideal product for both do it yourselfers or professional roofers. Made from 99.2% pure zinc and includes bag of 26 1-1/2" zinc nails.