Thermo is Stokely Discs’ opaque premium plastic, built to combine durability with grip across weather conditions. All seven Stokely moulds are listed in it, and the Cardinal and Peregrine come only in Thermo.
It covers the two things players usually trade against each other: premium wear resistance, so a disc holds its flight longer, and a tactile surface that stays usable in rain and cold. That makes it the default Stokely plastic for drivers.
It costs more than Strato and beats in slowly, so it isn’t the plastic for a disc you want to wear into a turnover. Strato is.