A simple guide to use these brushes to clean: 1. the large brush: water bottles (narrow opening brush like S'well bottle), vases, mason jars... 2. the medium brush: baby milk bottles or pacifiers, beer bottles, soy sauce bottles... 3. the small brush: kettles, cans, jam jars... 4. the cotton straw brush: glass/steel straws or delicate surface surfaces... 5. the sisal straw brush: bamboo straws or surfaces with tough stains... A reusable water bottle is far better than wasteful bottled water. However, if you do not clean your reusable water bottle regularly, then it could harbour harmful bacteria with black mould that could make you sick. Unwashed bottles can accumulate bacteria and can be dirtier than dog bowls and kitchen sinks. Care Tips Please refer to the last product image