Mondopoint. The International Standard is ISO 9407:1991, "Shoe sizes—Mondopoint system of sizing and marking", which recommends a shoe-size system known as Mondopoint. It is based on the mean foot length and width for which the shoe is suitable, measured in millimetres.
FYI, the focus should be on these are M28 , the shells , both cuffs and lowers have "Range" markings that will only confuse you , especially if MondoPoint is not familiar.
Enough to say these are good boots , in good condition from a good BOL member. Feel safe in buying from him.