Hard Blok is a specially formulated, cement-based material that provides maximum strength, vibration dampening and heat dissipation required in high-performance race engines. Hard Block auto block filler also extends cylinder wall life both by preventing cracked walls and by causing the walls to wear truer, honing is minimized during rebuilds. Remains stable at all operating temperatures and does not soften when exposed to high heat and will not erode under water. Hard Block auto block filler is Non-toxic, non-corrosive and contains no hazardous chemicals.