I just checked after work today.... my 1.5OC was claimed when one of my razors sold. I have that second generation, very rough and uncomfortable 1.5SB, at least, for me.My Yaqi 1.5 SB is on the very mild side, the 1.5 OC not, with a different cap. So I would say the SB is first gen and the OC something else.
P.S. sorry, I had so many alerts yesterday, I missed your question!