A composition having: 30% to 35% by weight of a first polydimethylsiloxane having vinyl moieties, wherein at least 0.10% by weight of the first polydimethylsiloxane is attributed to the vinyl moieties; 20% to 25% by weight of a second polydimethylsiloxane having vinyl moieties, wherein at least 0.20% by weight of the second polydimethylsiloxane is attributed to the vinyl moieties; 7% to 10% by weight of a third polydimethylsiloxane having hydroxyl moieties, wherein at least 2.0% by weight of the third polydimethylsiloxane is attributed to the hydroxyl moieties; 22% to 35% by weight fumed silicon dioxide, wherein the fumed silicon dioxide has a surface area of at least 150 square meters per gram; 0.2% to 1.0% by weight a blowing agent; 0.15% to 0.5% by weight active boron; and 0.25% to 1.00% by weight active peroxide.