A stainless steel water bottle is a gift that works when she actually needs one because she is the sort of person who forgets to drink water otherwise. Stainless steel insulation keeps drinks at temperature for hours which is genuinely useful. The design needs to be simple enough that it is easy to clean and carry without being fiddly. A good bottle does not leak and the lid closure feels solid. These are the stainless steel water bottles that justify a gift because they encourage a habit that is actually good for her.