There are both current and voltage ratings for low voltage. They may also be referred to as jack, plug, or receptacle.
Barrel type

PL03A(Barrel type)
A (External shape):5.5mm
B (inner diameter):2.5mm
C:9.5mm
PL03B(Barrel type)
A (External shape):5.5mm
B (inner diameter):2.1mm
C:9.5mm
PL03C(Barrel type)
A (External shape):5.0mm
B (inner diameter):2.5mm
C:9.5mm
PL03E(Barrel type)
A (External shape):3.8mm
B (inner diameter):1.35mm
C:9.5mm
PL03F(Barrel type)
A (External shape):3.8mm
B (inner diameter):1.05mm
C:8.0mm
PL03G(Barrel type)
A (External shape):3.5mm
B (inner diameter):1.35mm
C:9.5mm