The Cx4 Storm was manufactured with multiple magazine well options:
1) Px4 (C5C620) – Product code # C89210 – This magazine well accepts Px4 magazines for use in Cx4 Storm however you may also purchase the 92/96 Insert to convert a 92/96 series magazine into a magazine that is compatible with the Px4 magazine well
2) 92/96 (C5A511) – Product code # C89109 – This magazine well accepts 92/96 series magazines for use in the Cx4 Storm however you may purchase the Px4 Insert to convert a Px4 magazine into a magazine that is compatible with the 92/96 series magazine well
3) 8000 8040 – Product code # C89110 – This magazine well accepts 8000 / 8040 series magazines for use in the Cx4 Storm however you may purchase the Px4 Insert to convert a Px4 magazine into a magazine that is compatible with the 8000 / 8040 series magazine well
Note: If you choose to use a magazine insert to convert a magazine to fit your Cx4 Storm, you will also need to purchase the required magazine button