YONGNUO LS-2.5 RF-603 N3 Shutter Release cable 2.5mm-N3 Shutter Release Cable Used to connect Yongnuo RF-603 N3 transceiver Used to connect other 2.5mm port receiver to your camera to achieve the function of wireless remote control. The unstretched length is about 30cm. The max stretched length is about 100cm.