The ROOK professional flash trigger can work as flashgun trigger, studio light trigger, Transmitter"s hot shoe support TTL flash,and can sync the receiver to trigger the flash on it. * It can remote control the camera, just like the wireless remote shutter release, support half-press focusing and full-press take the picture. The shutter control support long time exposure.(BULB mode). Supports to control multiple cameras to take shots at the same time. * ROOK is using global free channel 2.4GHz and FSK modulation system to make the performance more stable, and work in bigger distance. Particular saving power design can make the transmitter and receiver battery last more time. * Transmitter has a 3.5mm input socket witch can connect with your camera"s PC sync port. in this case, you can keep on use your hot shoe and trigger the other flashes. Receiver has a 3.5mm output socket. It can be use to connect your camera"s shutter remote port(Need extra shutter connect cable), or connect the studio flash via attached 3.5mm to 3.5mm sync cord, or connect with the flash via PC sync cord (need to purchase extra 3.5mm to PC sync cable). * Support the TTL flashgun wake-up function; you"ll never miss any shot opportunity. Flash sync speed Max to 1/320s. Operation Distance Up to 200 Meters