The fear of Iraqi forces from Gesher in the east and Jenin in the south to form a "spearhead" and capture the Baysan and Jezreel valleys convinced the Jews to take Zir'in.
The intermediate reflector is a layer (IRL) of Zinc oxide (ZnO intermediate reflector: ZIR) or Silicon oxide (SiOx intermediate reflector: SOIR) between the top and the bottom cell.