... Corrosion-resistant galvanized steel 3. Changable velcro pre-filter Ventilation Accessaries, Carbon Filter 4'' 6'' 8'' 10'' 12'' Available ... Parameters:* Corrosion-resistant galvanized steel* Changeable velcro pre-filter* High grade activated charcoal* Over boxed in corrugated cardboard ... adjust a wing, etc.), ventilation products (flexible duct inline fans, etc), grow bulbs (including HPS and MH), ...