Delicious cooking with less fat. The real advantage is the closed cooking system. Simply cut the tube to the desired length. Then add food such as fish, meat and vegetables. The OptiVit® valve allows the hot air to escape from the roasting tube in a safe and regulated way during the cooking process. Perfect for cooking succulent, wonderfully aromatic and delicious meals. And if you use a Toppits® roasting tube or roasting bag, you can also take delight in having a clean oven.