Boss 363 Sealant Acrylic Latex Caulk with Silicone is a silicone caulk designed for both interior and exterior use. Boss 363 Sealant Acrylic Latex Caulk with Silicone forms a tough, flexible resilient bond to all building material surfaces. Silicone caulk has excellent resistance to water, weathering and moisture vapor. Boss 363 cures to produce a flexible seal that is non-yellowing.