According to the description in the package:
Purpose: This product uses the latest Bioelectric Impedance analysis (BIA) technology to immediately and automatically detect the factors affecting the skin conditions, such as moisture, oil, softness and displays the result on the LCD screen with convenient graphical illustration and description for the user to understand. Normally, the food, health condition, lifestyle and external environment are used to affet our skin conditions.
What is BIA?
BIA is the abbreviation for Bioelectric Impedance Analysis, which employs bioimpedance as the measuring theory (impedance belongs to one of the resistances in which, the non-conductore effec is also involved) to determine the percentage of Fat-free Mass (body liquid and electolyte) and fat mass (fat does not contain water) in our body tissues.
What exactly does this gadget do?
It actually measures the water content, oilyness and the softnes of your skin. I think this thing is faily accurate, because I've measured my oilyness early this morning and it gave me a standard value (i.e. normal), and I've measured my t-zone again in the afternoon and it was full on the scale (i.e. very oily).
Honestly, I've bought this in 2006 and it was mainly for fun, I hardly ever use it....