I've run all three in my 50cc'ers and can't tell any difference at all. The black rubberized one holds up OK on E10 fuel but does get a little stiff after about a year or so (I assume from the ethanol in the fuel). I've never worn out a "Tan" Teflon one or the "Blue" Acetate one. I have a couple of carbs with the synthetic materials and they seem as good as the first day I put them in; both the blue and the tan.