From Wikipedia:
Magazine capacity
To keep in line with the introduction of laws in some locations restricting magazines that hold more than 10 rounds, Beretta now manufactures magazines that hold fewer than the factory standard 15 rounds. These magazines have heavier crimping (deeper indentations in the side) to reduce the available space while still keeping the same external dimensions and ensuring that these magazines can be used on existing firearms.
Italian magazine manufacturer Mec-Gar now produces magazines in blue and nickel finishes with a 18 round capacity, which fit flush in the magazine well on the 92 series. Mec-Gar also produces an extended 20 round blued magazine that protrudes below the frame by a 3/4 of an inch. These magazines provide users in unrestricted states with an even higher capacity.
There are 32 round mags that will fit a 92.