Yongnuo RF-603NII-N1 Wireless Remote Flash Trigger Kit for Nikon D800 D700 D300 D200 D1 D2 D3 D4 The new RF-603 II is improved version of RF-603, it is a remote shutter release as well as a multi-functional flash trigger which can synchronously trigger flashes and studio strobes. Through the transceiver based system each item can be used flexibly as trigger or receiver. Only 2 AAA batteries are required as power source for each item. The 2.4GHz wireless frequency is suitable in most countries and guarantees high speed, distance and stability. Within capacious areas, the remote control distance may reach to 100m. The synchronization speed can reach to 1/320, depending on the situation.