What is a bolt with a star hole in it?

A star shaped hole is a Torx, Their sizes go, T8-(T10-T15-T20 most common) upto...T50. There are bolts that the head looks like that and they are sized the same but with the designation "E" instead of "T". All tool manufacturers sell them, as they are becoming more popular with newer cars. Lisle makes a nice $/value set.