Owner Comments:
This is just a place holder example not a coin that I own. Photo credit to Conder101 NGC generations thread. The key differences between generation 1 and generation 2 holders are; the generation 2 holder took the foil logo that was on the front of the gen 1 holder and moved it to the back. The solid core was changed to white and a white label was used on the front of the slab for the coin information. According to the research done by Conder101, both of the generation 2 holders were only used for a month or two, from the end of November 1987 Thru some portion of December 1987. Given that there is still a decent size extent population of both of the generation 2 holders I tend to think both were used for a bit longer than the timeframe Condor101 gives. There is an informal excel spreadsheet that lists each known example of the generation 2 holders. Clearly that list likely does not have every surviving generation 2 holder on the list, but the last time I looked there were several hundred of each of the generation 2 holders listed.
In his original research Conder believed this to be the first of the generation 2 slab style to be used by NGC, and thus labeled it 2.0. However, it is now believed that this was actually the second of the generation 2 holders. That thought seems very likely to me as this holder uses the same reverse foil logo that is embossed on the outside of the holder vs the inside of the holder as it is on what Conder called gen 2.1. To me, logic would conclude that NGC would not have used the foil logo on the outside of gen1, then the inside of the first gen 2, only to reverse course and put the logo on the outside again on the second gen 2 holder.
However, NGC has (to my knowledge) not published any documentation or has any digital reference (like the PCGS museum of holders) on how or when each holder design change occurred. So the system of numbering is biased on the observations of the collectors and dealers that were actively in the market since (while) NGC has been in operation.
This generation, like the gen 2.1 is very expensive; but I hope that I will be able to find a example that I can afford one day.