Using this water bottle carrier bag is a breeze. First, slide your 40oz tumbler or water bottle into the main part of the bag. You can attach the detachable pouch to the bag if you want to carry extra items like your phone, keys, or ID cards. Adjust the strap to a comfortable length according to your body size and wear it across your body or on your shoulder. When using the small pocket for bank cards and other essentials, make sure to zip it up to prevent loss. As for maintenance, you can spot - clean the polyester fabric with a mild detergent and a damp cloth. Keep it away from sharp objects to avoid tearing. Remember, the color of the actual item might be slightly different from the preview images, so don't be surprised if there's a minor variation.