8G bottle cage must use sunken nuts. Normal screws will scratch the bottle. Stronger and flater tail hook to hold the bottle . Warning: Do not press the cage when it is empty, bottle inside will support the cage better. Use standard size bottle to avoid over extrusion. 74mm or under bottle is recommended. Do not fetch the bottle brutally. NOTE:This product is suitable for weight reduction on bicycles. If you need a high-strength water bottle cage, please choose an alloy material. Colour:Carbon Fiber Black Material:Carbon fiber + metal Package Contents: 1 x Bike Cycling Water Bottle Holder Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.