The size of the mask is medium (M-100mm) which almost fits all adults.
The anti fog is a chemically imposed activity and UNMASK being a healthcare product we have limitations of its imposition and thus it work best above 25 degree C temperatures at 25 or below it vl start fogging and sudden change of atmosphere might also give some fogging which can be cleaned using a cloth or tissue paper.
The validity depends on the usage and conditions it is kept in.
The mask filter is made from N95 mask materials the same 5 layer with carbon layer in the centre for extra filteration.
For 72-80 hours of active usage that too in normal conditions and atmosphere!
Wash the mask with tap water only every time you wear it by removing the filter.