Born of 100% steel (and a good bit of bravado), the Sub-Zero PRO 48 with Glass Door Refrigerator/Freezer is a true masterpiece of preservation. Its glass door, sculpted metal, dual refrigerator with three evaporators and advanced controls marry performance and design in a bold new way for home refrigeration. I saw a similar glass door commercial fridge in a home, and although it looked fabulous, the homeowners had to live with loud humming that usually accompanies heavy duty appliances, not so with this beauty!