The Mk 55 service mine and the Mk 55 exercise mine are air-laid bottom mines. Each mine is fitted with a nose fairing and box fins for drop stability. Each is suspended from the aircraft by two suspension lugs spaced 30 inches apart. Both mines use a parapak designed to slow descent and reduce impact when the mine enters the water. A control unit, activated by a single arming wire, opens the parapak. Each mine is equipped with an arming device and a double arming wire used on the extender and hydrostatic switch. The Mk 55 mine is equipped with a firing system that is responsive, either singly or in combination, to the acoustic, magnetic, and/or pressure influence of a passing ship. The Mk 55 exercise mine is an inert service mine equipped with exercise components.