The Plug-in Photocell is compatible with all Professional Series, Contractor Series and Plus Series transformers. Used for automating on and off sequencing, it features a dusk to dawn lighing sensor that turns the lights on when it gets dark outside and turns them off when it gets light. Ideal in exterior transformer installations. Compatible with Kichler's Professional Series, Plus Series and Contractor Series transformers. Includes mounting hardware on transformer knock outs, as well as a 3-inch cord. Features a male-ended plug. What's in the Box: Mounting hardware and a 3-inch cord.