This syle of overnight bag comes with a Cover over the Zip.  They are great for going on the back of the ute and keeping out the water and dust.  I will never claim that it will keep every thing out, but these come close.

the bag comes with 2 zip pulls so you can put a lock into them to lock the bag.

The Overnight or Weekender carries enough clothes for a long week-end.
It features a heavy duty zip and handles which go all the way around, under the bag, hidden by the double layer base which ensures durability.

Approx 60cm L X 29cm W X 29cm H