The BAM mount is intended to provide Aimpoint M4 sight’s with multiple distance settings.
5.56/223 Ballistics: 50/200 Meter Zero, TO 800 Meters
As the integral Aimpoint twist mount moves parallel with the sight, the Aimpoint dot will always be centered in the magnifier or NV device that is attached. For use in low light, the 50/200 meter setting has one afterglowing dot to quickly and easily show the user that the sight is correctly adjusted.
The ambidextrous knob on the BAM has a visible and fellable “tongue” so that the user knows when the “tongue” is in it’s rearward position. At the 50/200 meter setting, the ballistic curves are the same, so when the gun is zeroed at 50 meters it´s also zeroed at 200 meters with that setting. This is for control purposes as it’s not always possible to get access to long shooting ranges. The BAM works equally well for rifles and machine guns.