This is the Elinchrom Skyport Speed USB Transceiver Mk II [EL19363] Part of the EL Skyport radio release system, this Elinchrom Skyport Speed USB Transceiver Mk II automatically searches for units with Transceiver RX modules or with built-in Skyport RX receivers and allows computer control and monitoring of the flash"s settings. Controllable functions include flash power setting in 1/10 f-stop or in individually settable steps, modelling lamp setting in 1/10 stop increments as well as proportional, free (manual) and power off, photocell and audible recycle alert on/off, standby and socket selection on RX packs. Features: Wireless Control for Mac or Windows Can Control all RX Flash Units 4 Selectable Trigger Groups 8 Frequency Channels 40 Bit Security Encryption Software Updates via USB Up to 164" Range Indoors Up to 394" Range Outdoors Specification: Compatibility Mac or Windows systems, RX Flash units and packs Channels and Groups 8 Channels, 4 groups Security 40 Bit encryption Connection USB A Frequency 2.4 GHz Range Indoors: 164" (50 m) Outdoors: 394" (120 m) ...Contact us if you need more help.