Originally installed a cheap petcock, found it did not really cutoff the gas when in the on off position. Lived with it up until some grit got into my S&S carb float chamber preventing the float to cut off the fuel. So when the engine was off not using fuel the gas kept flowing even with the petcock valve off. This was the old petcock I paid little for. So I bought this expensive nice one from Dennis Kirk which solved the problem. Plus this one has an even better fuel screen to prevent grit from even getting to the carb.