Breathe Bell Tents are made from 100% cotton canvas. As this is a natural material, there may be subtle variances in colour or minor imperfections. These imperfections do not affect the overall performance of the tent. When it is brand new, the cotton may let some air through and leak a little around the seams. Once the canvas has been wet, the cotton expands, making the tent 100% waterproof. Cotton canvas provides a natural waterproofing and breathability. Cotton fibers swell when damp, the tight weave prevents rain from penetrating and the surface tension of moisture on the outside combined with the angle of the canopy allows water to run off. Moisture held in the air on the inside is still able to escape directly through the fabric, keeping internal humidity low and mitigating condensation.