QUANTIFOIL® Multi A is a holey film, in which a pattern of various hole sizes, shapes and arrangements is repeated. In addition to circular holes, the pattern includes oval-shaped ones which appear round at high tilt angles (~70°). The circular holes have diameters of 1 µm, 1.4 µm, and 2 µm. The elliptical holes measure 1 µm x 4 µm and 2 µm x 8 µm (along the shortest and longest axes, respectively).