FAMASIL FR-VM is a synergistic composition of vinyl and methacryl organosilanes in combination with organic peroxide and siloxane-based processing aid. The bifunctional silanes provide chemical bonds between inorganic substrates or fillers and the organic polymer. FAMASIL FR-VM improves mechanical and electrical properties in mineral-filled polymers due to the chemical connection to the filler resulting from the bifunctional silanes. The combination with organic peroxide provides an additional curing or grafting of the polymer system. Hydrophobising of the fillers results in an improved dispersion and compound processing which is highly beneficial for the Advanced Materials industry.