Specifications: ZSD18-B / 1.8 Liter / 250 Watts ZSD20-B / 2.0 Liter / 300 Watts The Steaming & Stewing Mugs are rarely unique. In fact, I don?t personally know another company that makes this product, but I haven?t looked for one either. What make this product special are its operational characteristics. What we had in mind when we created this product, was a true stew and steam chamber that was perfect at doing its job. Isolation, heat, moisture, and control; all free from external influences was designed into this capable appliance. Water is added to the inner pot with your food, and then the pot is covered with 2 lids. Water is then added to the outer pot, which is also covered. The steam environment on the outside of your pot balances the steam environment in your inner pot. Nothing goes in?nothing comes out. The result is delicious. Enjoy!