Black Jacket, Hosa Pro Metal Connectors This Hosa SKJ-400 Series Premium Speaker Cable is a 2-conductor cable built from high quality OFC oxygen-free copper wiring and is used to send a clean signal to non-powered speakers or monitors. It features Hosa's own Hosa Pro metal 1/4 phone connectors at both ends. It is intended for high-current applications only; not for line-level signals.