I've been researching this for weeks now. I know for sure they are D2S size. What I'm wondering is how much the factory's fade over time. I had a Cadillac before this Infiniti and the lights were way brighter. Granted both cars were bought used. So I have no idea of how much night time driving was done. I was told to go for the Osram 66240CBB. Kinda pricey at about $190 a set...but they are supposed to be the best. As it sits, my low beams with fogs are brighter than high beams (fogs turn off with high beams...but thinking of rewiring them to ignition...sort of like DRL) .