I have both of these. The SM802 I have had for years but, bought the MW802 a year or so ago to make sure I have correct readings. Probes must be stored correctly, or they will need to be replaced every year or 2.
SM802
http://www.amazon.com/Milwaukee-Smart-Combination-Meter-Model/dp/B000EOOPWQ?tag=greenrel-20
MW802
http://www.amazon.com/Milwaukee-Instruments-MW802-Smart-Combined/dp/B004CZ8664/?tag=greenrel-20