When it comes to the best fiber for the tent’s walls, there’s perhaps nothing which is as good as the Oxford 600D cloth. This is the best in the business and is more or less an industry standard. Anyone who makes grow tents these days mostly uses this cloth. In addition to that, the inner reflective layers should ideally be Mylar layers as close to 100% reflective as possible. Most grow tents use between 95 to 99% reflective mylar layers.