Hopefully last post on this... so DGX is arranging to ship the black rings to me. Based on correspondence with DGX, they apparently will get these rings from Max @ Cavemax.com. Not certain, but seems logical they may have got the kits from that same source as well.
Subsequently, DGX is updating their website "per Rolock to remove the black ring as part of the package. You can still purchase them separately; however, they are no longer part of the package.".
IMO, your results may vary depending on where you buy and their sourcing. As I mentioned previously today, Rolock still shows the 90-9091 kit including both blue and black rings.