... and backpacks. What is it with the backpacks?
Umbrellas are used by Antifa to blunt the use of pepper spray. Backpacks are for storage of a change of clothing for when they vanish after action. The change to non-black and also it’s useful for carrying bottles of caustic liquid etc. They will also carry a bottle of milk for washing out eyes when they do get pepper sprayed or tear gassed. They can also conceal a collapsible baton inside the backpack.