If you wear contact lenses, you also purchase Saline Solution on a regular basis.  There are many brands to choose from but they all contain the same ingredients so the brand name is not important.  One brand is not better than the next.  Since it keeps contacts clean for the health of the person wearing them, the solution is consistent in its manufacturing.  It comes in various sizes for convenience.  For home use, a large bottle could be purchased but for travelers, smaller travel size bottles are available in a kit that will help you stay organized while packing.  Many sizes helps people with their different needs.