Using global free 2.4GHz channel and FSK modulation system, and there"s 16 selectabh frequency channels. Flash sync speed is up to 1/250s. Maximum operating distance is up to 100 meters. * Support the flashgun wake-up function; you"ll never miss any shot opportunity. (Wake up can only used in TTL Compatible flash). * Fire the flashgun through hot shoe part and fire the studio light through mini USB socket. * Low voltage design, it"s able to use rechargeable batteries. Power supply use 2*AAA batteries.(transmitter and receiver)