Integrated Marketing Group style 3500 is an industry-strength heavyweight fiberglass fabric, made with a plain weave. This versatile fabric is available in two high-quality finishes: loom state, or a very light clear acrylic coating. The uniquely-designed light acrylic coating is applied in order to reduce raveling and fraying of cut edges. This powerful fabric was specially designed for use in areas where a heavyweight fabric with high heat resistance is required. FM APPROVED