3M™ Fire Barrier Moldable Putty Stix MP+ is a one-part, ready-to-use intumescent firestop containing a synthetic elastomer. The intumescent property of this material allows 3M™ Fire Barrier Moldable Putty Stix MP+ to expand and help maintain a firestop penetration seal for up to 4 hours in the event of a fire. It is often used to fill voids in large openings and/or complex firestop systems due to is moldability, re-enterability and smoke-seal properties (provides a draft and cold smoke seal for systems with L-Ratings). 3M™ Fire Barrier Moldable Putty Stix MP+ firestops penetrations passing through fire-rated floor, floor/ceiling or wall assemblies and blank openings. In addition to excellent thermal- and fire-resistance properties, 3M™ Fire Barrier Moldable Putty Stix MP+ helps minimize sound transmission through assemblies requiring an STC rating. 3M™ Fire Barrier Moldable Putty Stix MP+ is easily moldable by hand and exhibits excellent adhesion to a full range of construction substrates and penetrants.