Pardon the noob ignorance, but what are the main differences in the 200mW Rayfoss handhelds? Searching their page turns up QBT, QMT, QST, QGT, FLX, CO3, BO3, FGB, SWT. And the FMK, but that is IR filtered, so I can see why it is $80 more than the next most expensive.
But what do all these...