A domestic and semi-professional form of quarter-inch (6.35mm) jack plug. Available with either two or three terminals and referred to as TS (Tip-Sleeve 2-terminal) or TRS (Tip-Ring-Sleeve 3-terminal). Widely used for electric instruments in an unbalanced mono format (TS), for stereo headphones in an unbalanced stereo format (TRS), and for balanced mono line-level connections on semi-pro equipment (also TRS).
Although similar in overall length and diamter to the professional B‑Type Plug, the two formats are not compatible. The large angular tip of the A-type plug will damage B-type sockets, while B-type plugs will not mate correctly with A-type sockets.
A miniature version of the A-type plug is also available called the Mini-jack, with a 3.5mm diameter and in both TS and TRS formats. Widely used for domestic headphone and input connections on consumer portable equipment, as well as for CV and gate connections on modular synthesizers.