How to tell the difference between volkswagon front and rear disc brakes?

I have a set of volkswagon disc brakes that i want to sell, people are asking if they are front or rear! i dont know how can you tell?How to tell the difference between volkswagon front and rear disc brakes?front ones have about an 11 inch diameter for the roter and the rear ones are about 6 inches.How to tell the difference between volkswagon front and rear disc brakes?Front pads are larger than rear.How to tell the difference between volkswagon front and rear disc brakes?the front are larger, but if you have only one set being front OR rear then i assume you have nothing to compare them with. What i would do is measure the discs diameter and then go to a car parts shop as if buying discs 4 the car all round. when they price them ask them what the difference is front to back and they will give you the sizes.