Please note that these filters look like a spring but are in actual fact fine-particle filters.
They are not standard equipment to all DHLA's but they can be fitted to all, which is recommended when you are encountering problems with not 100% clean gasoline / petrol and your pump jets clogging up.
They simply drop into the pump jets before fitting the plug.
Required quantity per carburettor: 2
This is item number 53 in the drawing.