I use the two Yongnuo YN-622C basic versions for some time and have now bought the YN-66C TX. As expected, all three device together without problems. adjusting the different channels is super easy and can be done without the study of English-speaking guide. Criticism: On all three device the necessary AA battery does not fit. Too much play, so that the batteries flying around in the use of the battery compartment and no contact is even made. Remedy: with something together wound aluminum foil between the battery and pole the problem was solved. There shall be deducted therefore a half star ... Otherwise - no problem.