'1/4'' MIL-plug mono connector (MIL-P-642/4), black metal housing, brass contacts. Professional telephone connectors with MIL type design according to MIL-P-642/* standard. They feature similar construction to standard Neutrik telephone connectors, with chuck-type strain relief and a thin metal barrel to meet the high requirements of military communications equipment. These connectors are not compatible with standard 1/4'' jacks (according to EIA RS453) or patch panels.'