RVR-VIS
Well its a very good question. Instead of asking the question, why not look up the answer. Do your self a favor and learn the information that is located in the Jeppesen 'General' section of the Airway Manual. Instead of putting your feet up, reading the newspaper or the latest edition of GQ, do some work.
If you were working with me on a long haul flight you might learn a thing or two.