He sells MBW/MBK Rolex reps, which are famous for being able to accept many genuine Rolex parts (crystal, crown, tube, etc) with little or no modification. While they are by no means perfect out of the box (all reps contain inaccuracies), they can be modified to come very close to looking like the real thing. There are scores of threads that discuss MBW watches & the modifications members have devised for them that you can find via the Search.