The Pocket Wizard PowerST4 Receiver is designed specifically for Elinchrom Style and Digital RX series lights* and provides remote power control capabilities when paired with an on-camera MiniTT Transmitter or FlexTT Transceiver. Power settings on your flash are adjusted simply by using the flash compensation dial on your camera or add the AC3 ZoneController to get three independent zones of power control capability. Once your flash settings are dialled in, ControlTL PowerTracking allows you to change shutter speed, f-stop and ISO and the system will automatically adjust power levels to maintain proper exposure. The receiver draws power from the flash and so doesn't need a battery. Using the PocketWizard Utility and USB connection, you can fine-tune the initial power settings, program your modeling light shut-off timing, change channels, or update your firmware.* (NOTE: Ranger RX, Speed and Speed AS require EL-Skyport Transceiver RX Adapter - not compatible with D-Lite)