The NP3TB-B is 1/4" 'B-Gauge' plug (BPO 316), black metal housing, nickel contacts The NP3TB-B has rated voltage of < 50 V and rated current per contact of depends on mating connector A and dielectric strength of 1 kVdc . Professional phone plug according B-Gauge standard BPO316. Featuring similar construction as the standard Neutrik phone plugs with chuck type strain relief and slimline metal barrel. These plugs are not compatible with standard 1/4" jacks (acc. EIA RS453) and patch panels.