The Magnetic Accelerator Cannon, also known as Mass Accelerator Cannon, MAC Gun and MAC Cannon, is a large coilgun that serves as the primary offensive weapon for UNSC warships. Larger versions are used as orbital defense platforms. MAC guns are the only non-nuclear weapons in the UNSC arsenal capable of effectively reducing or destroying Covenant capital ships' energy shields. Smaller shipborne versions can take as many as three hits to overload a shield while an orbital platform can put a hole through any Covenant vessel even with fully charged shields. The Magnetic Accelerator Cannon should not be confused with the Railgun, despite their superficial similarities. An Onager-class cannon is capable of disabling a CCS-class battlecruiser, with its shielding down.