Underside of <a href="https://en.wikipedia.org/wiki/en:Certification_listing#Firestop_Configuration_D" class="extiw" title="w:en:Certification listing">Assembly for UL certification listing C-AJ-8073 Configuration D</a>, the mortar is intact, the fibreglass has disappeared and the intumescent wrap strip has occupied the space formerly held by the insulation.
<a href="//commons.wikimedia.org/wiki/User:Achim_Hering" title="User:Achim Hering">Achim Hering</a>
2007-06-25
<span class="int-own-work" lang="en">Own work</span>