This tire is a Mitas XT-444 300-21. This is a limited production tire that has more knobs which means more studs! It is still the white strip winter rubber compound, but in a tougher XT tire casing. We only have a limited number of these special pattern tires. These studs have a mushroom shaped base, steel body and carbide tipped protrusion. At our warehouse we drill the holes, we inject bonding glue and then use a unique machine to insert each stud. This same process is used in Europe. It is very time consuming. Beware of the imitations! When you want the best front grip in the XT series - this tire IS IT. This studding pattern is the PRO EXTREME model - 310 STUDS.