They also have the additional benefit of not creating a positive or negative pressure difference between inside & outside. This helps prevent air being forced through many unknown holes in your house's air/thermal barrier which could draw moisture into the wall cavities and promote mold & rot. Hope this helps.

Dave

M60v3, VP100v3, QS8v3, EP350v4, Onkyo TX-NR905

M22v2, Vector Research VRX-9000 stereo

AxiomAir