Does anyone here know if there is a grading system for schrader valve cores? I had a little fun with this at Johnstone one day by asking the guy at the counter if he had any grade #1 cores because all I saw on the shelves were the black grade #2 cores. I proceeded to tell him that the color of the core designated the grade and that the red ones were #1. It sent him looking for a grade or color designation from his supplier, which he didn't find. It does make sense to me that there should be a grading system for them if for no other reason than temperature.