Search the forum for "versaflo". Lots of information. With the versaflo you will need a separate, belt worn, air supply unit. The Trend has everything in the helmet which means it is heavier on your head but a lot less cost. Much on this subject has been posted in the past couple of years. You can find comparison threads. I just got the Versaflo 307 helmet, new, from Ebay for a lot less than on Amazon.