Ever get to the check in for your luggage and be over by one stinking pound?  They want to charge you an arm an a leg for it or you have to reshuffle your baggage like an idiot taking out shoes and putting them in your carry on.  This little baby is compact, light and you can throw it in your handbag once you've determined your bag is at the right weight.  Has not failed me yet, and I fill my bags within an ounce of the limit.