Materials and construction are very similar to the original Panasonic C-18 dust bags, both inside and out. Both appear to be made from the same type of fabric with a pleated cotton filter lining that feels the same in every pocket. The Panasonic case in these photos weighs 25 grams, while the Envirocare weighs 27 grams, which is essentially the same given manufacturing tolerances and scale error. I'm not able to measure airflow or filtration, but I have no reason to think there would be much of