Many times can't be carried onto a plane, whether in personal item luggage, stowed in a carry-on, or on your body. Those items include gel candles, liquids (in quantities of more than 3.4 ounces), sharp objects, large amounts of alcohol (more than 3.4 ounces), guns and ammunition, and tools (such as wrenches, screwdrivers, and pliers) that are longer than 7 inches. Sports gear like bats, skis, snowboards, golf clubs, and self-defense items like mace or pepper spray cannot be taken in a carry-on or personal items bag. You'll also want to leave the chemicals, flammables, and explosive items home.