The Andromeda II Footprint by Exped protects the tent floor from abrasion, dirt, water and sun. Shaped like, but 10 cm (4") smaller than, the tent floor to prevent rain from collecting between footprint and tent floor. Also covers the vestibule floor space to protect the vestibule from dirt and humidity. Attaches with adjustable, elastic cords.
Used as a Tarp: a footprint doubles as a tarp against rain, wind and sun (that is, against excessive exposure to UV radiation whether at high altitudes or in dry, sunny places like Australia and New Zealand).