The ProMaster 200ST-R Speedlight works with your camera to provide powerful light, TTL exposure, and a wide range of advanced features including HSS high-speed sync, second curtain sync, and more. The articulating head can be adjusted for a variety of swivel and bounce positions; and is compatible with many light modifiers. The 200ST-R's powerful guide number of 60m/200ft combined with 200mm zoom head can illuminate subjects from afar. The built-in wireless 2.4 GHz radio TTL system provides expanded off-camera lighting options when commanded by a ProMaster ST1 transceiver. Wireless non-TTL (F1 and F2 modes) optical slave is also on-board. - Maximum output power: 500 lx-s at 10' / 3m (at 200mm zoom position) - ProMaster 3717 USB firmware downloading cable for computer connection