Bosch black stainless is made from a special material, not just a foil coating and helps guard against scratches and fingerprints to maintain its bold look. Converts to Recirculation Mode with Accessory Kit (Separate Purchase Required). 2 Halogen Lights - 12 Volt, 20 Watt Max., G-4 Base. When the vent hood is installed in recirculation mode, the air is picked up and passes through multiple filters including the charcoal filter that absorbs odors. This freshened air is then pushed back into the kitchen. Over time, activated charcoal particles saturate and stop blocking off odors leaving your kitchen with strong smells.