Can anyone tell me what the 2 parallel black rings around the outside surface of the OEM supercharger nose bearings are for?

Rubber seals built into the face. Not sure why it'* there.

Will any problems arise if I replace the OEM bearings with new bearings that don't have those 2 black rings on the outside, and is there a special part number or letter for bearings that have those 2 black rings?

Well, considering the SC oil passes through both bearings and is held back by the seal, I don't see why the rubber is even there.

The few of us who have rebuilt our nosedrives use aftermarket bearings without that feature. No problems here.

Go for it. I'm not aware of a supplier for the OEM bearings.

Thanks for the info, willwren. I'll plan to use SKF or NSK bearings that don't have those 2 rubber rings.

Since we're delving into "Bearings 101" topics, I'm also curious about bearing speed ratings. The nose bearings are to be C3 rated, and I always assumed that was a speed rating, but I began poking around the net to learn more about bearing ratings, and it seems that the C3 rating is a clearance rating, not a speed rating. So how do you select a bearing that has a specific speed rating such as 18,000 or 20,000 RPMs as needed for the supercharger nose?

Well, you can save yourself some grief and simply order the bearings from one of our common suppliers. I'm spinning at around 18000 rpm'* at my raised red line on the SSEi, and have had no problems so far. My nosedrive temps aren't any higher than they were before the SC rebuild.

I already ordered them from a local distributor earlier this week.
Can anyone tell me the part numbers printed on the bearing package and/or the numbers on the bearings themselves?

All of the part numbers are in a topic here in Forced Induction.