2.5mm refers to the approximate diameter of the connector. 2.5 and 3.5 mm connectors look very similar, differing only in size. Last updated Dec 7, 2013 by Rich Brome Editor in Chief Rich became ...

Some phones offer only a 2.5 mm jack, which is a smaller variety of the same principle. Headphones supplied with mobile phones usually have a mic somewhere along the cable and a remote button that ...