If you are interested in trying to use European LED tubes with LED starters in any of your preheat fixtures without modifying the wiring so that you can go back to fluorescent as desired, here is a tutorial video that can help you:
https://youtu.be/AN2mjPyLaAwNote that the LED tubes that work in European 2 lamp series F18T8/F20T12 fixtures can also be used to retrofit a North American 120v F20T12 preheat fixture using the original choke since a North American F20T12 tube on a 120v choke ballast is electrically identical to the European 2 lamp F18T8/F20T12 series setup on a F36T8/F40T12 choke designed for 220-240v mains supplies.
