These are our least expensive, most lightweight and compact electronic transformers. They will fit where other types of transformers cannot. In fact, some models are small enough to fit inside a fixture housing or attached electrical box. To prevent voltage drop, we highly recommended mounting within 10' of the last light fixture in the circuit. They work with most trailing edge or reverse-phase type AC dimmers (on primary line-voltage side) rated for inductive loads. Some versions are available in an "R" version which has extra RFI filtering. Not recommended for use with LEDs.