This beautiful object has become indispensable in our stay. The sensor is really effective because it automatically detects the change of ambient air (kitchen, use of nail polish .....). Operation is simple as not being technological I managed in 5 minutes. The rear panel retires to put the filter. Can be set to automatic or manual mode if you want the filter to be more or less powerful. When the ring is red, is that the air is polluted if it is blue. It is discreet and I no longer sneezed repeatedly and my daughter for her presence. My hairdresser at home has noticed the change on the way home before they even submit the purifier!