I suspect that's what 150% means. The original 100% that the old bulb was giving plus another 50% extra. Otherwise they would say 21/2 times brighter, which would be a lie. 150% brighter sounds amazing, but also isn't legally telling a lie, so perfect sales jargon. That's how I read it, anyway.I've just switched to these and they make a lot of difference to night driving on country lanes but I'd say in real terms they only seem about 50% brighter than standard halogen.