now i think the shurflo backpack is the best thing ever, but it does have one major downfall, and that is it has no handle to carry it, OK on the trolley its fine, but there's places where the trolley cant get into to, so its a matter of removing the backpack from the trolley, if its full of water this can be very strenuous on the arms, shurflo should add a handle to it, so when lifting it, it stays balanced, as it is now we have to lift by the straps, and some times the straps come loose, and that's another pain, i am certain that is what caused my arm injury, over 2 weeks of work because of this bad design
