Shogyo offers a unique line of DC Power Connectors with a quarter turn locking feature.  These are recommended for any application in which a completely secure connection is required.  They are especially useful in rugged applications whereby a disconnection cannot be risked by simply tugging on the cord.  Below, please see some photos to illustrate how these work.

Here are links to the product pages. 

2.0MM DC JACKS:

MJ-10LR

MJ-179LR 

SCD433CCS000B00G

SCD442CCS011B00G

SCD442CCS013B00G

SCD443CCS011B00G

SCD443CCS013B00G

2.35MM DC JACKS:

MJ-11LR

MJ-180LR

2.5MM DC JACKS:

SCD433DCS000B00G

SCD442DCS011B00G

SCD442DCS013B00G

SCD443DCS011B00G

SCD443DCS013B00G

2.1MM DC PLUGS

MP-121AR

MP-121CR

MP-121LL

MP-121MR

SCDP442CBNN0000G

SCDP443CBNNNBPTG

2.5MM DC PLUGS

MP-122AR

MP-122CR

MP-122LL

MP-122MR

SCDP442DBNN0000G

SCDP443DBNNNBPTG