The MiniRail XPRess mounting system for solar modules is designed specifically for trapezoidal sheet metal roofs. Coming in small lengths of rail (17 inches) allow maximum flexibility and ease of installation. 17-inch sections of rail with EPDM backing to reduce the chance of water intrusion. Self-tapping screws also have an EPDM washer to reduce the chance of water intrusion. Can be used on metal sheet roofs as thin as 26 gauge, special order for 29 gauge.