sentences:  These old magazines are not compatible with new grip modules; the accessory rail was changed as well from a curved rail to a Picatinny rail.The factory holsters of the original grip modules do not fit newer grip modules featuring Picatinny rails though the modular nature of the firearm allows the original grip modules to be easily swapped out with the new version inexpensively.In 2012, SIG Sauer introduced a medium width version of the subcompact grip module with the Picatinny rail.