If you're not packing too many things, this bag might do just fine. It only comes in one colour, green, but it does look quite neat and it has a volume of 30 litres.
From Amazon
Fjallraven 23802-664 Kånken Weekender Sports backpack Unisex Frost Green Size OneSize
Scandinavian Outdoor Store
Fjällräven Kånken Weekender
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