FlashWave-III Wireless Radio Slave Transmitter (Transmitter unit for Remote Wireless Flash Trigger System) - Transmitter unit Simple, Small, Reliable! Even greater operating range than FlashWave-2. Up to 600 feet (185 meters)! Max sync speed of 1/250s. 16 Channels. 2.4 GHz operating frequency FlashWave-III Receiver unit is sold separately.