When replacing awning roller tube or fabric, most cases you can open your awning and on the roller tube it should have the brand and the model number which is the easiest way to get the correct size and specific color if replacing the same color.
In the instance you are unable to get that model number; you can always measure by specifying the center of arm to center of arm measurement and NOT the length of the fabric or roller tube; also is there is a metal weathershield with your awning and is there is color on both sides of the fabric (for fabric replacement).
If you are in need of further assistance, contact a local authorized service center or contact the manufacturer's technical support.
Per the manufacturer these awning replacement fabrics are hand rolled and put in tubes rather than boxed, avoiding wrinkling and creasing to the fabric. These Dometic replacement fabrics will ship via freight truck, so please plan accordingly.
"Fabric length" is based off of the length of the whole awning (i.e. 85074XX.072) which will determine the "size" of the fabric needed. The actual fabric will almost always be a smaller measurement than the awning length.