The strength of 600D polyester varies depending on coatings and the crossweave of the fabric. A standard 600D polyester bag can withstand approximately 15 pounds of force before tearing. 600D polyester is a strong fabric but not as strong as nylon of the same denier.
The D in polyester ratings refers to denier, which is the weight in grams of 9,000 meters of the yarn used. Crossweaving with a lower strength polyester such as 300D, decreases the tensile and tear strength of the material. When high endurance material is needed such as motorcycle gear, the preferred fabric is nylon or kevlar because of its high abrasion rating.