Blackstone Indoor Remote Controlled Outlets Set of 4 Indoor Remote Outlets Wireless Remote Control WRCS14 Outdoor Power Stake and Remote Package Includes: (4) Wireless Wall Outlet Receivers (Receiver Units) (1) Four Button Hand Held Remote Control {Sender Unit) (1) Battery Type: DL2032 Features: Blackstone Indoor Remote Controlled Outlets operate on a radio frequency and are not dependent on line of sight. They will perform regardless of walls, doors, and floors.