Avoid it like the plague!
I bought a modular "Ebay" helmet (VCAN brand) as my first helmet. Second time out on the bike, I wiped out going about 40 mph into a ditch. According to the eyewitness, my brand new made in China modular helmet slipped OFF my head (strapped down and locked into place) before I hit the ground. I suffered a broken nose and several cuts on my face as a result. And the thing was strapped on tight, too! Thank goodness I didn't directly hit my head on the ground, or I would be dead right now.
It came off because the locking mechanism wasn't a locking mechanism at all. After the crash, my brother in law could simply apply pressure to the chin guard and it would pop out of its locks. This is because the lock hooks were made of cheap (bendable) plastic, and the locking bars were made of cheap (bendable) plastic. So when my head bounced backwards, the wind caught under the helmet, flipped the modular mask open, and just the right combination of forces made the thing slip backwards off my head. (We re-created the event, and sure enough even with the strap down tight it still slipped right off my head). I was sent their top-of-the-line (which is still pretty cheap) full-face non-modular helmet as a sort of "we're sorry our product was so cheap and almost killed you". I now wear a Nolan.
So, if you're going to invest in a modular helmet, spend the money for a good one. At the very least an HJC, or even better a Nolan or Shoei. You'll thank yourself later after it doesn't come flying off your head in a 40mph crash.
*edit* I should mention that the helmet I bought off Ebay was ALSO DOT approved. So honestly, I don't think the DOT folks know much...