Just trying to determine if it is a Benq or Asus....
I had a friend purchase several of the Cendyne drive the 48x and 52x series. What he discovered was that when it says. 4816a or 5224a on the box it as a ASUS model. When he picked one up that said 4816p it was a Benq model.
Also he discovered that the 5224 w/o (a) was a Aopen drive. So it so far appears to be the (a)= Asus, p=Benq and no small letter = Aopen.
Also the LTR as previously mentioned is Liteon.
Hope this helps.