I have 2 brand new sets of Seattle Sports Fast Pack panniers, four bags in all, which are said to be 750 cu. in. each (10x14x5). They are orange and claimed to be waterproof, roll down tops like dry sacks. They are PVC free, unlike the Ortliebs and some others. In addition, I bought a rear rack trunk bag and handlebar bag (both black) by Avenir, and they are only claimed to be water resistant; I will treat them with silicone spray or scotchgard. I haven't used any of these bags at all, but they were substantially less expensive than the brand name offerings. I will have to get you an update on durability when I have one.