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. 2021 Aug 26;11(8):e049605. doi: 10.1136/bmjopen-2021-049605

Figure 3.

Figure 3

Hygiea power box dissembled to visualise specific components and direction of air-flow (as indicated by the blue arrows). The prongs on the battery side (A(a)) press the high-efficiency particulate arrestance filter into the lip of the filter side (B(a)). A ridge on the hose connection increases seal integrity and prevents accidental disconnection (B(b)).