What is High-quality 600D Oxford fabric? 

Not all 600D Oxford fabrics are the same.
Article explains key basics: “D” (Denier) is a unit for chemical fiber fineness.
Common 600D Oxford fabric is 600D×600D polyester plain fabric, but it’s made by twisting two 300D yarns (300D/2) instead of one 600D yarn. This twisting makes the fabric softer, more durable, and easier to produce.
Article also covers regular 600D varieties, reasons for price differences, common coatings and functional finishes, plus its uses