Last year I purchased a RW-4 from Fishstreet and it promptly went in the drawer. I have recently purchased a RW-4 from a UK store and the controllers are different. Part of my purchasing the second RW-4 was because the controllers are supposed to be able to be linked wirelessly, similar to my old MP10s. The older Fishstreet unit has a black controller with RW4/8/15/20 on it and the new one shows W10/20. These units don't appear to be able to talk to each other! I have tried to contact Jebao on their support email, but they fail to reply. My UK seller has said "This WM10-20 is for the new style RW4 you have, its compatible, but may not be compatible with your other RW4. " Seems to me that the new RW-4 is not a RW-4 at all and there appears to be some sharp practice on the part of Jebao. Perhaps these new units should be called the W10 and not the RW-4?