What it does: A durable bicycle carrier bag that keeps essential items organized on your bike and secures extra gear on the outside with an elastic luggage cord. Key benefits: External elastic cord on the top: quickly secure raincoats, protective pads or other items for easy access and fast packing. Large internal capacity: stores a small tire repair kit, rear light, gloves, tissues, phone and even a drink — so you ride prepared without extra backpacks. Durable construction: made from polyester with foam reinforcement for long-lasting wear resistance and gentle protection of stored items. Broad compatibility: designed to fit most bicycle carriers and racks, including mountain bikes and road bikes. Practical features: Keeps frequently used items within easy reach while riding. Foam structure helps maintain shape and protect contents from light impacts. Elastic top cord expands to hold bulky or irregular items securely. Typical use scenarios: 1. Daily commute: carry your phone, tissues, gloves and a small drink while keeping a taillight and quick-repair kit ready for unexpected needs. 2. Weekend ride or group tour: stash tire repair tools, spare gloves and snacks inside, plus attach a raincoat or extra pad to the top cord for changing weather. 3. Short errands: transport a drink and small purchases securely on your bike carrier without needing a backpack. Materials and compatibility are consistent with the original specifications: polyester and foam construction; suitable for most bicycle carriers such as mountain bikes and road bikes.