This Kenro wireless radio signal flash trigger system enables hot shoe mounted or camera synch. Cable operated sender module which enables the photographer to control up to 4 or 8 heads (depending on the kit) switchable on or off. One battery operated flash receiver is included; receivers for up to 4 heads are available. Effective operating ranges Approx. 15-30 metres. Both the 4 & 8 channel kits are available in either battery or mains power versions.