The "S" version of the 400 Series – as with the 300 Series – is the smart model. That means it has WiFi integrated, and works with Coway's app. Unfortunately that's a little underwhelming.

Check out this review of the Coway Airmega 400 air purifier from an editor who suffers from a pollen allergy.

Both the Bidetmega 400S and 500S feature Coway's i-wave cleaning technology, a multi-stage wash care system that customizes water pressure, motion, and spray patterns to suit each user's ...

Coway’s heated seat, heated water, auto-cleaning, blow-drying, and night-light-laden throne is a masterpiece of comfort and cleanliness I now can’t live without.