Condo firewall device?

Saw this in a 30 year old condo in the firewall between two units, the attics have gable venting. Looking at this it appears that the metal plates which are like an accordion will expand and close the opening in the wall. Is that its purpose?

There were no markings on it. Ideas?



Did it have fusible links - such as mechanical ventilation vent with a fusible link damper? Fuse melts and shutter closes based on temperature rise.

i’ve seen those. they usualy melt at about 160-180 deg.