Rainguard Blok-lok 1 Gal Clear Penetrating Silane Siloxane Professional Grade Water Repellent Sealer - Concrete, CMU, Block, Brick, Stucco, Stone for Vertical Applications, Apply Low Temp 35F & Newly Poured Concrete, 5 Yr Warranty Labor & Material Warranty 5 Years Does not alter surface appearance and will not yellow When applied, Blok-Lok forms a long-chain water repellent barrier deep within the masonry surface This hydrophobic barrier repels water yet remains highly vapor permeable and allows moisture to escape 100% Eco-friendly: low VOC &lt;15 g/L, low odor, no cancer causing materials