The Hahnel Modus 600RT MK II Wireless Kit for Micro four Thirds includes: Modus 600RT MK II Speedlight, Viper TTL Transmitter, 1x HLX-MD1 Extreme Battery, USB powered MD1 Ultra-compact Charger and a USB cable. This wireless speedlight kit features a fast recycle time of 1.5sec, up to 600 shots at full power, up to 1000 shots at 1/2 power, wireless connectivity, a built-in 2.4GHz wireless receiver and transmitter, and compatibility with many other speedlight brands through Viper TTL. Use alone or as part of an on- or off-camera speedlight array.