C-purlins are structural components that help support roofing systems. They are shaped like the letter “C” and are primarily used in the construction of buildings to provide a framework for roofs. The 75x45x15mm dimensions refer to the size of the purlin, where the width is 75mm, the height is 45mm, and the lip is 15mm. This specific size is ideal for various roofing applications, providing strength and versatility.