Heavy-duty. Ideal for larger applications. Double internal channels with cross girder adds additional protection. Easy to install. 4-1/2" Overall height. Highly durable double internal channels and cross girder extrusionProtects against heavy impacts and provides a large contact areaUV Inhibitors and Fungicides prevent fading, yellowing, deterioration from sunlight and unsightly blotchingUnaffected by oil, gas or saltwater