I was unaware of many things relative to this whole LED light bulb endeavor. I appreciate the additional insights. All I know is that I bought them, installed them, and they worked. I knew about the need to match bulb sets so as to avoid activating the Bulb-out warning, but I was unaware that the BFS in our older model Volvos were not so sensitive as I had supposed. In previous threads on or related to this subject, there were some who had apparently installed some LEDs and then had the BFS activate. I don't presently recall if those individuals installed matched sets. Some of the information put forth on the matter - at the time - speculated that the very low power draw somehow "tricked" the BFS into "thinking" that their was no bulb there. Since I don't know enough about the subject to speculate intelligently, I'll just be glad that I managed to stumble onto a working combination. As for the possibility of other LED suppliers making similar shunt resistor LED bulbs, I certainly hope so, because I paid 20 bucks a pop for each of mine - ouch!