A real fan spinning inside a puck, so the white noise is a natural, non-looping whoosh that never repeats or glitches.
The Dohm has been lulling babies (and adults) to sleep for decades, and the reason is simple: it's a mechanical fan, so the sound is genuinely random air movement instead of a digital loop that can develop an audible hiccup. There's nothing to update, no app, no battery to die mid-nap, and it tends to outlive the baby stage and migrate to a grown-up's bedroom. Downsides are real: it only makes one kind of sound (fan whoosh), it has no light or timer, and it needs an outlet, so it's not a travel piece. Skip it if you want nature sounds, lullabies, or a night light in the same box. If you just want the single most reliable white noise a room can have, this is it.