LED Drivers are a type of transformer and electrical device which are used to regulate power to LED's, string lights, sign lights and other electrically powered devices. LED Drivers are available in a wide range of configurations and sizes to help accommodate the todays all types of DIY projects and new fixtures designs. This LED Driver has a "120 Volts" Input Voltage which is converted to "27-42" Volts. (AC/DC) Measurements 3.5" Long x 1.61" Width x 1.24" Height. This LED Driver is "dimmable" from (100% to 1%) without flickering. Dimming is accomplished by reducing the amount of current going through it or by or by PWM. PWM is Pulse width modulation and uses a rectangular waveform and variable positive duty cycle to adjust the brightness or the LED proportionally. Our LED Drivers are made with quality parts that are fully potted. Potting helps protect the internal components from being damaged in the event they are exposed to the elements. Always make sure to check LED input requirements when setting up a new circuit using an LED Driver. Always make sure power is off when working with electrical parts and fixtures.