OCLV carbon construction. Ultra-lightweight at 29g. Streamlined shape. Secure hold. The Pro Carbon Water Bottle Cage is perfect for racers and long distances, ideal for hill climbers who want a lightweight cage that securely holds their bottle, whether on the road, bumpy roads, or rocky terrain. Suitable for both road and MTB, you're sure to find the perfect one from a wide range of colors. Product Details: OCLV carbon construction Securely holds bottles, perfect for road and mountain bikes Includes lightweight aluminum alloy mounting screws I only attached it to my bike once and then removed it for storage without using it. Please consider it.