Here's what other sites are saying:
The MSR Twin Sisters Footprint is a ground sheet for the Twin Sisters 2 tent. Give your tent a floor, since this tent doesn't even have one in the first place. Probably pretty handy on rainy days, or whenever the ground is damp from the day before. Camp and explore another day. Features of the MSR Twin Sisters Footprint Cut slightly smaller than tent floor to prevent pooling of water under tent during rainy weather Webbing stake-outs at tent corners provide easy attachment
Add a floor to the ultralight Twin Sisters 2 person tent with the tent footprint.
- Mountains Plus
You got the Twin Sister Shelter because you appreciate its lightweight compactness, and unfortunately a floorless design comes with that convenient lightness. So when you know the campsite is going to be wet and muddy, be sure to pack MSR's Twin Sister Footprint. MSR made it out of the same material used on the shelter, so you know you can rely on it when wet weather is in the forecast.
Made of water-resistant polyester-taffeta, MSR footprints protect your tent floor from sharp objects, such as rocks and pine needles, as well as from mud and ground water. They also increase the versatility of most MSR tents by acting as a ground cloth in lightweight tarp-style setups.
MSR Twin Brothers Footprint
Hilleberg Kaitum 3 Footprint
Mountainsmith Morrison Footprint
$22 - $23
Eureka! Floor Saver Square Medium
ALPS Mountaineering Tasmanian 2 Floor Saver
$23 - $26
Black Diamond Ahwahnee Ground Cloth
$37 - $49