This is a great kit that incorporates all of the essentials you need in a quality strobe system. This kit comes with two Digital 2400RX Power Packs & Flashhead Twin X4. Some of the advantages to this package are: Fast recycling to full 4800 ws flash power: 1.9 s. Integrated “RX” interface for EL-Skyport / wireless power control and triggering. Fast flash duration at full 4800 ws: 1/600 s. Twin X4: Twin cables and flash tubes to connected to two 2400 ws packs. Also included is an EL-Skyport RX Trigger Set consisting of 1 Transmitter and 2 Transceiver RX Modules. This system enables you to have complete control over your strobe from camera position. The capabilities of the skyport system are amazing. Great range, up to 395 feet outdoors and easy operation make this a joy to use. You also can adjust the output, modeling light and separate heads on up to 8 channels.