There is a potential deadly issue with the plastic grill burner knobs on the Weber Summit Grill . The burner knobs operate to turn the gas on and off for each burner. 3 of the 6 knobs have cracked on our grill, so they no longer work to turn the gas on or off for the burner, they simply spin freely without turning the gas flame up or down, on or off. It becomes a deadly issue if the knob DOES work to turn the gas on, but then the knob cracks after turning it on and will not work to turn the gas off and therefore the gas could accumulate in the grill and create an explosion hurting or killing someone. This product should be made of some type of metal that will not crack like the current plastic knobs. Weber offered to send new burner knobs, but that does not solve the issue since the new ones are also made of plastic. I am very concerned someone is going to get seriously hurt or killed by a gas explosion from failing (cracked) burner knobs.