Weed mats consist of two sheets of fiberglass-reinforced craft paper with a semi-permeable medium between them. They are 36” x 36” and have an X-cut in the center. The mats are semi-permeable, allowing moisture to reach the ground while slowing down evaporation and wind desiccation from the soil immediately surrounding your planting. The mats will decay in 4-6 months, completely decompose, and disappear within 12 months.