Traditional Culture Encyclopedia - Traditional festivals - What is the name of the cloth bag on the backpack as a waterproof one?

What is the name of the cloth bag on the backpack as a waterproof one?

This is called - waterproof cover, there is this means that your backpack belongs to the needle car type of ordinary backpacks, their own can not do waterproof, can only rely on accessories (waterproof cover), but this kind of waterproof means is very general, not to say the trouble is not also impractical. Can only be a short period of time to prevent a light rain. If you need all kinds of waterproof luggage recommend a brand to you - OSAH (OSAH) Hope to adopt, thank you