Steel Perforated Return and Exhaust Air Grilles with Filter Model: ZYAGF-B Steel Perforated Grille with filter lock systems type Frames are made of extruded aluminium. Rigid,heavy gauge extruded frames with reinforced mitered and welded corners.Aluminium eggrate grille core or steel perforated grille core,other grille cores are available. Powder coating finish,standard colour RAL9016.RAL9010. Other finish are available. Filter:Non-woven fabrics or Nitrilon,or aluminum mesh Sizes manufactured on request Back Side