Remote trigger can be used for studio flash and outdoor flash. The trigger unit comprises a transmitter and a receiver. The transmitter mounts onto your camera #39;s hot-shoe, and the receiver is attached to the studio flash light by 6.35mm or 3.50 plug. Triggering voltage is ultralow, and allows you to use the unit for a year without having to change the battery inside.; Designed by ball-shaped hot shoe contacted point, which can protect camera well; Characterized by easily operation and long-distance remote control, standby and trigger signal indicators. Features : 1. 4 Channels to avoid interference; 2. Transmitter -- 12V-23A; 3. Receiver -- 2 x AAA-1.5V batteries; 4. Working frequency:433MHz; 5. Max. working distance--30m (Open area without interference); 6. Max. Sync Speed - 1/200 - 1/250s(depending on camera andflash); 7. Works for majority of older flashes used with film cameras; 8. Warranty time:12 months;