This is a standard established by the Japan Electronics and Information Technology Industries Association (JEITA). It is used for low voltage and has both current and voltage ratings. It may also be referred to as a jack, plug, or receptacle.
EIAJ standard 4/5

PL05A(EIAJ-4)
A (External shape):5.5mm
B (inner diameter):3.3mm
C:9.5mm
D:1.0mm
PL05B(EIAJ-5)
A (External shape):6.5mm
B (inner diameter):4.3mm
C:9.5mm
D:1.4mm