Applications:

top quilts/blankets, underquilts, sleeping bags, pillows, jackets, lightweight bags, hammocks, and much more.

Understanding Breathable Fabrics

Allow air to readily pass through them, allowing sweat to evaporate and keeping you cool. 

Fabrics that hide sweat are frequently breathable to aid in reducing sweating.
Help you stay dry and comfortable when you sweat.
Fabric weight and fiber composition are two factors (amongst others) that influence how breathable a piece of fabric is. 

While nylon fabric is light, its fibers are so tightly-knit that air cannot pass through it.