FlashTrig 16 Radio Trigger for Studio Flash. Up to 30 m working distance. 16 channels can be selected. Sync speed up to 1/250 second. 433 MHz radio frequency. Box contents: transmitter, receiver with 3.5 mm jack plug, 3.5 mm to 6.35 mm plug adapter, sync cable, 23A / 12 V battery for transmitter. Reciever requires 2 AAA batteries (not included).