Protect the floor of your tent and extend its useful life. It's sized to fit the floor of the Big Agnes Tumble 1 mtnGLO Tent and designed so it doesn't channel rain under the tent. It also allows you to use the fly without the tent's inner body, for an ultralight configuration when conditions permit.
The standard test for coated fabrics uses a standing pipe (column) filled with water. The figures given are the water column height. A 1000mm coating allowed no leaks after 1 minute under 1000mm of water.