DewStop is a fan switch that monitors humidity and dew point levels in the bathroom and switches the fan off or on to help minimize water damage to walls and stop the growth of mold. DewStop's Condensation Sentry is triggered when steam becomes too heavy for the air to support and moisture is accumulating on walls, mirrors and fixtures. The switch is easy to install and features a 30-minute timer, as well as a manual on/off switch.