The NewerTech Guardian Maximus (GMax) houses two hard drives internally, and can be hooked up with eSATA, Firewire 800 or Firewire 400, and USB 2.0, so it can be connected to any Mac out there today.
But you don’t need to understand RAID or do anything special at all, because it just appears as a single drive to your Mac. No special software, no special setup. Simple.
With a RAID-1 mirror, if one of those two drives dies, the GMax just keeps running with no loss of functionality. At that point, backup any data, and contact OWC to get the failed drive replaced. With a 3 year warranty and 48 hour warranty service, it offers great peace of mind.
Of course, any external unit also has a power supply that can fail, so no protection is perfect. But the GMax at least takes care of the headache of losing data from a hard drive failure, since both drives are very unlikely to fail at once (barring a lightning strike or similar event).