Featuring a 2.4 GHz wireless radio receiver, the Yongnuo Flash YN560-III Speedlite is a long range manual flash unit capable of being triggered from up to 300? away with the YN560-TX, RF-603, and RF-602 wireless transmitters. The YN560-III 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.