Brand new in box. $25 or best offer
Description from company website: Perfect for traveling through airports with your car seat and child in tow. The car seat attaches effortlessly using the LATCH connectors—the same connectors that secure your car seat in your vehicle. Designed with a compact fold, the travel cart fits into small spaces, including most airplane overhead compartments.
More info and photos: https://us.britax.com/shop/car-seat-accessories/car-seat-travel-cart