Featuring both a 2.4 GHz wireless radio transmitter and receiver, the Yongnuo Flash Gun YN560-IV Speedlite is a long range manual flash unit capable of triggering other flashes from up to 328? away as well as being triggered with the RF-603 and RF-602 wireless transmitters. The YN560-IV is powerful with a guide number of 190? at ISO 100 and 105mm. The unit is also quite versatile with a zoom range of 24-105mm, which is able to be expanded to 18mm with the built-in wide-angle diffuser. Additionally, this output can be adjusted from 1/1 to 1/128 power in 1/3 and 1/2 EV steps.