GRP Felt Trim Internal Angle - Type 4 Black Description Internal Angle - 200mm x 200mm. This is a glass reinforced polyester roof edge trim, designed to provide a weatherproof, decorative finish and strong clean lines to the roof edge, it has a high glass fibre content giving a low coefficient of thermal expansion,solving the problem of splitting and leaks at the roof edge.  Provides permanent colour and resists corrosion and the extremes of atmospheric pollution and is quality assured throughout the production process from raw material to finished product under EN IS0 9002.