The Shelly Bypass is a module specifically designed for use with the Shelly 1L and Shelly Dimmer 2 in installations with no neutral wire if the total wattage load is less than 20W for the 1L or 10W for the Shelly Dimmer 2, meaning that these devices can work perfectly even at lower voltages. ***Please note: The Shelly Bypass isn't required if your installation includes a neutral wire, even at low wattages.