CoPilot is a user friendly wireless TTL Flash Controller With Auto-Focus Assist. CoPilot (QF91C) for Canon & CoPilot (QF91N) for Canon DSLR cameras. Photographers can now trigger and quickly set ratios for three groups of radio controlled Qflash. Set lighting ratios on the fly, right from your camera. Simply turn three controls on the CoPilot to instantly adjust lighting ratios as you shoot. The CoPilot controls 3 independent remote flash groups without a local flash, or 2 remote groups with a local Qflash connected to the CoPilot accessory socket. Each flash group can be set to Manual or TTL. Power and ratio settings are easily controlled by a dial for each flash group. Good news for photographers still using their older Qflashes (T2D,T3D T4D, T5D). The CoPilot gives you the ability to use your old flash as a local flash while still getting the TTL ratio control of remotes offered by the newer T5dR and TRIO. Remote flash groups consist of Quantum TRIO, Qflash T5dR, or any non-Quantum flash that can be triggered in Manual and Auto mode only, by a FreeXwire wireless receiver. Add any number of remotes to any remote group. Mix and match all the flashes you own. CoPilot controls remote Qflash TRIOs or T5dRs. And it triggers any combination of non-Quantum flashes connected to a Quantum FreeXwire receiver.