Comment by Y_Y

Ironically this appears to be because another company wanted to protect its trademark.

> In the United States, Tefal is marketed as T-fal. This is to comply with DuPont's objection that the name "Tefal" was too close to DuPont's trademark "Teflon". The T-fal brand is also used in Canada and Japan.

The alphabet T is pronounced "teh" in French. So insofar as the French company is concerned, T-fal sounds close enough to Tefal.