The Guideline Pro 2 Footprint protects the floor of your tent from abrasion, dirt and humidity. Designed specifically to fit the Guideline Pro Tent.
MSR says:
Custom-fit protection for your tent floor, providing increased protection from water and wear-and-tear.
MSR Footprints protect the groundsheet of your tent from damage caused by rough terrain. I would only usually consider one if I knew I was going to be camping on stony pitches.
