Using a footprint not only protects you from rocks, sharp twigs or pine needles, but also from mud and ground water. It will also minimize condensation caused by dampness in the ground of the vestibule. Can also be used as tarp keeping you out of the rain, wind and sunshine. This is Eureka's footprint for the El Capitan 4 tent.
Tent Floor, Eureka's El Capitan 4 Tent