I love the bag. Of course this is my first bike, so this is my first tail bag.  Don't have much to compare it to, but I know I would buy it again if I ever happen to lose this one or something.  This bag fits on my GS500F and it doesn't move while I'm riding.  I can fit my lunch box, water bottle and the liner for my mesh jacket in it without expanding it.  I can also fit my boxing gloves, hand wraps and towel. I've also put a pair of sneakers, reflector vest, jacket liner and water bottle.  I've yet to expand the bag.  It comes with a rain cover. I got caught in a downpour without the cover and my stuff was fine.