The single layer mask in Figure 2C is of unknown 1.0-mm thick material, of a design which was cheaply and widely available. Compliance with CWA 17553 was not claimed. The CE-marked FFP1 respirator mask in Figure 2D has no exhalation valve and it is marked as complying with EN 149. The CE-marked type 2 medical mask in Figure 2E had a metal nose clip which was cinched down firmly on the dummy. The packaging was marked as complying with EN 14683. The bandana or neck gaiter in Figure 2(f) was 0.33 mm thick 100% polyester and was folded into three layers in these experiments. Dating from 2019 this was never intended for infection control, although the same material has been seen to be used as a face covering.