The Dusk to Dawn LED GLS light bulb from ProLite employs a light receptive sensor to recognise the time of day and subsequently turn on/off accordingly. Features a ES-E27 Edison screw (27mm) base/cap.It emits a warm white light at 600 lumens, representing an efficient, retrofit alternative to existing compact fluorescent equivalents. Please bear in mind that the system operates based on light it receives from the sun, making it ideal for fixtures that receive ample natural light. No manual adjustments are required, simply insert the LED GLS light bulb into an existing fitting and allow the system to adjust. Also known as an A65 light bulb.Need more help in choosing a suitable light bulb? Read our guide What is a GLS Light Bulb.