150db is how they are rated. I don't know how they rate or test them at the factory, however; I have a fried who is employed by the county and he works in enviromental monitoring. One time I asked if he could measure the sound level and he had me drive over to where they were doing clandestine observations with a serious sound meter and give some blasts. When they looked at the chart or whatever it shows up on, the sound they were monitoring which was a moto cross race track was pretty loud and right where I blasted the horns there was a spike that completely drowned out the moto cross racers. Measure in at 160db. As he explained it to me that level for sustained periods of time is a bad thing. I've tried it on guys in cars with boom boxes that make their fenders rattle and you feel the sound in your guts a block away, they can hear my horns.