Product review (1 stars): Overall they were terrible. They come with different adaptors for various cooktops
Overall they were terrible.  They come with different adaptors for various cooktops, but once you have the adaptors inside the knobs, the knobs turn only with great difficulty.  Also the silver dials shown in the pictures aren't actually a part of the knobs but a slim piece which slips over the top and won't stay in place very well.  Spend the extra money for a better grade.