Metacaulk Putty Pads are used to maintain the hourly rating of fire-rated walls containing electrical outlet boxes and to reduce sound transmission. Only one pad thickness (1/8 inch) is required for a 1 or 2 hour fire rating. No additional putty material needed to plug the end of each electrical metallic tube or conduit at its connection to the box. Hand moldable with no curing time required. STC rating 60, Tested in a UL 411 wall assembly/section to ASTM E90.