B-Type Plug

A professional form of quarter-inch jack plug derived from the telecommunications industry where it is known as the PO316. It has three terminals (tip-ring-sleeve) and is widely used for balanced connections on professional patch bays. Although of similar overall length and diameter to the domestic A-type plug, it has a much smaller tip and is incompatible. A miniature version is available for high-density patchbays, called the TT or Bantam jack-plug.