The personal item bag on Spirit Airlines is not as large as some other airlines, but passengers are still allowed to bring a few items with them. The bag must be small enough to fit under the seat in front of you, and it can be no larger than 16"x14"x12". You are also allowed to bring a carry-on bag, which must be able to fit in the overhead bin.   Some of the items that you are allowed to bring in your personal item bag include a purse, a laptop, a diaper bag, and a small backpack. You are also allowed to bring food and drink onboard, as long as it is sealed and does not exceed 3.4 ounces. If you have any questions about what you can bring onboard, you can always ask a Spirit Airlines representative.