Elastomeric, ready-to-use, single-component, neutral-cure silicone sealant that cures upon exposure to atmospheric humidity to form a flexible firestop seal that also acts as a barrier to airborne sound transmission. Seals construction joints and through penetrations in fire-rated assemblies. Provides up to 4-hour fire protection. Light gray color, ^+ 13% movement capability in joint systems. When properly installed, product provides up to 4-hour protection against the spread of fire, smoke and noxious gas in tested and listed systems. In addition, this product acts as an acoustic barrier by minimizing noise transfer (STC-Rating of 56 when tested in a STC 56-rated wall assembly), helps create a smoke seal for installations requiring the optional L-Rating, meets the intent of LEED(R) VOC environmental regulations, meets International Building Code (IBC) and other key life safety building code requirements.