Rotary inversion axis - labeled “N” with a “bar” over it, indicating a rotation of 360°/N plus an inversion through a center. Shown here is a 3-fold rotary inversion axis (“three bar”), in which an element is rotated by 120° (the intermediate position is indicated by the “dashed” structure) followed by inversion through the center (dashed red line). Successive application of the 3-fold rotary-inversion produces the collection of six molecules on the right, three at an “upper” level (signified by the +’s) and three at a “lower” level (the -’s). Notice, also, that the inversion causes a right-handed molecule (R) to be converted into a left-handed molecule (L).