The DOT bubble adjustment centered left the beam way too low. Since its such a sharp horizontal cutoff you can raise the beam up considerably, and its all focused straight ahead instead of diffused like the DOT beam. The horisontal adjustment works fine though, I didn't really change that. I don't know why there's a difference in the part numbers, but the boxes are factory sealed with Volvo stickers on 'em. The lens have Volvo and E4 instead of Volvo DOT on them. Maybe a call to FCPGroton can give better answers. All I know is, they are 100% better than the DOT lens and they work for me. Mike