The 3M™ Fire Barrier Self-Locking Pillow FB249SL is a self-contained, intumescent product that features interlocking strips that allow quick and secure pillow installation in floors or walls. The 3M™ Fire Barrier Self-Locking Pillows remove easily when adding new services. These self-contained, intumescent pillows are for use in a wide variety of through-penetration firestops including cable trays, conduit and blank openings. They provide up to 3 hours of fire protection. During a fire, 3M™ Fire Barrier Self-Locking Pillows intumesce (expand) and lock themselves into place, surrounding the penetrant(s) to help prevent the spread of smoke, fire and toxic gases. These easy-to-install fire barrier pillows are ideal for projects requiring re-enterability of the firestop system. Pillows can be simply removed and replaced as needed. Any combination of small, medium, or large pillows can be used to firestop an opening provided the minimum compression requirements are met (minimum of 33% within the opening).