I purchased an earlier version years ago for the 20D and it worked perfectly. I recently bought two copies of the newer unit for a 70D and a Canon Rebel. Out of the box, one receiver did not get a signal from either transmitter. I called customer service, explained the problem, and Ken immediately offered a replacement which, on arrival, worked perfectly. I understand things fail for numerous reasons but I judge quality of a company ultimately by its willingness to stand behind its products. Well done!