Aura 1808 18" concert sub was rated at 4" peak to peak, 2" one way at 800rms //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Very efficient motor structure and super lightweight cone. Of course everytime I got it to actually hit around 4" peak I cracked a cone haha! Was sick to see though. By the way Phoenix guys, I have another 1808 at the house now and have a new basket assembly coming for it so I will have to do a vid soon //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif It is pretty sick!