Two filter canisters are issued for the FM12, as with the S10; a light pressed metal type for riot control situations or training (marked with a painted red stripe or red tape), and a heavier plastic-encased type for protection against CBRN agents.

The characteristics it shares in common with the S10 are the fail-safe drinking device, two speech transmitters (one primary integrated in the exhale valve at the front, another secondary at the side port for telephone communications), and the ability to accept corrective lenses on the inside of the eyepiece.

The main noticeable difference between the FM12 and the S10 is the ability of some FM12's to mount two filters to the mask simultaneously, as was done by the SBS in the Gulf War.

The harness of the FM12 consists of elastic strips, which connect to a mesh fabric piece on the back of the wearer's head.

This variant is very similar to the CT12, except it has a built in microphone in place of the drinking port for operations where communication is necessary.