They are also hard to find now. Since some years ago, LiteOn produces drives under the HP and Plextor brand names, so any 12x BDRE drive you found would be an iHBS_12 model. So HP BD 335i or HP BD 340i, Plextor PX-LB950SA or PX-B950SA. (External versions of those are the same drive, as well.)
Optiarc BD-5300S and Sony BWU-500S.
Generic OEM models that were meant for pre-built computers (from Lenovo, HP, Dell, etc) and are sold as DH12B2SH or similar (as Oinker mentioned).
Those are the popular ones. ASUS also rebadged the iHBS drives, but used LG drives as well. So there are early ASUS BW-12B1ST models which are LiteOn, and later versions which are LG, and I don't think there's a reliable way of knowing which is which until you get the drive and install it.
There might be others I've missed, but I think those models are fairly inconsequential.