In a chimney flue, a damper closes off the flue to keep the weather (and birds and other animals) out and warm or cool air in. This is usually done in the summer, but also sometimes in the winter between uses. In some cases, the damper may also be partly closed to help control the rate of combustion.
A little more detail will help us answer your question. If your snacks are pretzels, potato chips, dried fruit or other dry goods, you can take them in your carry-on or checked bag. Snack items that are liquids or gels, like pudding, jello or yogurt, etc., falls under the 3-1-1 rules for liquids for carry-on bags. They can be transported in checked bags.
Use the 3-1-1 rule to remember the allowances on liquids you can take on board. You can carry on liquids or gels in 3.4-ounce or smaller containers in one clear, quart-size plastic bag with a zip. One bag can be carried on board per traveler. Medications, baby formula, milk and food are treated separately, and you may carry on larger amounts outside of the ziptop bag.