A coilgun was a type of weapon that accelerated a physical projectile using magnetic fields produced by coils of wire around the barrel. The 23rd century Bajoran Militia Karaya-class class cruiser mounted two spinal coilguns fore and aft that fired 5 kilogram rounds. (Bait and Switch: "A Changed World") In the 25th century, the Starfleet's T-204 Hayes main battle tank featured a 120 millimeter coilgun as its primary weapon. It was capable of putting a bunker buster shell through eight meters of ferrocrete. (Bait and Switch: "Last Rights")