Barrel – Audio adapters are used to convert from one audio connector style to another in both free hanging or panel mount versions. Examples include audio connectors with the same or opposite gender, MC1F, MC1M, phone jack mono or stereo 6.35 mm, 3.50 mm, phone plug mono or stereo 2.50 mm, 3.50 mm, 6.35 mm, RCA jack or plug, and 1.3 mm, 2.1 mm, and 2.5 mm ID connectors.