Broncolor RFS 2.1 transmitter
The transmitter slides onto your camera hotshoe or connects to shoeless cameras via the included sync cord. The RFS 2.1 has 40 discrete channels to choose from; more than enough to eliminate interference or overlap in multi-photographer events. 99 studio addresses are available. Besides a test button, the transmitter provides power up / down buttons to regulate the output in full stop or 1/10 stop increments on flash units controlled by it. The easy-to-read LCD display shows channel, studio address and power status of the system.