Product review (5 stars): Excellent Product
These are very functional, have an easy to slide cover that moves back-and-forth to indicate "CLEAN / DIRTY", it looks very nice (almost as if it were a part of the machine..why don't they make these manual indicators as part of the machines?) and it seems to be very durable.  However, PLEASE BE AWARE that they are adhesive backed and would be "permanently" attached.  Very useful and aesthetically pleasing; I bought two more to give to family.