PENNGUARD 55 Block is a foamed borosilicate glass block. As an inorganic glass it is highly resistant to acids, solvents, and weak bases. The material is made as a closed cell foamed glass block and is virtually impermeable to liquids and gases. PENNGUARD 55 is lightweight, and retains low thermal conductivity even when immersed in acid. PENNGUARD 55 Block is often used in conjunction with PENNGUARD Adhesive/Membrane and associated primers as a component of the PENNGUARD Block Lining System. Consult Corrosion Engineering specification CES-350 for complete installation details.