Auralex Acoustics STOPGAP Acoustical Sealent - Water-based Sealant for Sound Transmission Reduction ( Packaging may vary ) Stopgap Acoustical Sealant is a highly elastic, water-based sealant used for reducing sound transmission at the perimeter of wall systems or around electrical box cutouts to achieve specified STC/MTC values. Stopgap is paintable and nonstinging meets ASTM C-834 standards for flame Stopgap comes in a large, 29 oz caulking tube and therefore requires a larger than normal-sized caulking gun, which can be purchased at any local hardware store Wall, Ceiling &amp; Floor Applications For best sound isolation, Auralex recommends incorporating the following products into your room construction in the options shown above