Parafilm is often used in the laboratory industry to seal Erlenmeyer flasks and petri dishes with. It keeps bacteria out the door, while it does allow fresh air to come in. The Parafilm is 10 centimers wide and available in two different lengths – rolls of 38 meters and cuts of 1 meter. Parafilm is very flexible and it’s possible to stretch it 3-4 times of the original length.