DURABLE AND WATERPROOF: The surface of the bag is made of microfiber cloth and 900D nylon, which is soft, wear-resistant, water-resistant/resistant to heavy rain, dust-proof, durable, high tenacity and easy to clean. The orange lining inside is also made of polyester. FIX BY FOUR VELCRO STRIPS: the bag is fixed stability by four velcros, two on the rod, two fix on the saddle rail. All velcros can be adjusted. The diameter of the seat tube needs under 4cm. REFLECTIVE ELEMENT AND HOLE FOR THE REAR LIGHT: There is a hole below the bottle pocket to hang the rear light. you are more safe when cycling. the bag has a pocket inside to put your bottle.(package not contained the rear light and the bottle) INTERNAL STRUCTURE: an opening on the lining can insert the object, a mesh pocket under the opening, a small mesh pocket on the side, a small pocket on another side, an elastic band can fix your objects. Size: 24 x 8.5 x 8.2 cm; Weight: 0.2 kg; Large Capacity: almost 1.6L; The zipper seam is flat and waterproof and the bag is waterproof Attention: the zipper style has improved and the star shape is replaced by the quadrangle shape. Feature Brand: ROCKBROS Model: C7-1 Material: Microfiber Size: prsq.24*9.6*10.5cm Position: Saddle Package includes: a bag Waterproof: microfiber material. Taillight holder and reflective elements Large Capacity: 2.5L Suitable for city bikes, mountain bikes, road bikes, etc. Waterproof The surface of the bag is made of polyester, it is resistant to light rain. Taillight holder design Attention: the package does not include the taillight and the bottle! Pocket inside The mesh pocket inside to store them separately. Zipper Slides Two zippers slides.