PureIllusion performed an audio analysis comparing sound levels of Crystalline against standard equipment - and the results are incredible! Air purifier audio level variance is imperceptible across all 6 purifier speeds. That's a win-win for our customers! Choose Crystalline by PureIllusion for quiet, clean, affordable replacement air filters compatible with IQAir HealthPro series air purifiers! #pureillusion #crystalline #airpurification #soundlevels #cleanair #iqair #healthpro