Okay, This is bizarre... I just posted the serial #'s to the registry for my 2 sets of KEF 107's One set of rosewood and second set black I recently purchased the black ones #004703 on eBay from an eBayer living in NYC I had purchased a KUBE for my rosewood 107's from an eBayer in Los Angeles about a month before. I hadn't looked at and taken a picture of the serial # for the KUBE until today. To my surprise, the SP2105 KUBE serial is #004703, the same as the recently purchased black KEF's. And to SimplySound, I just realized the pictures you just posted on 1/18/18 are of my eBay purchase! It was a last minute bid and I got them for $571.00. And, yes, the serial number from one of the heads is different. The eBayer said that he thinks he has the KUBE in storage and will send to me when found. I'm beginning to think he might have sold the KUBE to the west coast eBayer a while back... I'm confused... One of the 2 heads does have a different serial # then the other 3 components. I guess these black KEF's would be the perfect candidate for recapping. From what I reading, the caps are not matched with the other head.