For the term from the electrical industry, see Industrial and multiphase power plugs and sockets#Twist-locking connectors.
A twistlock and corner casting together form a standardised rotating connector for securing shipping containers. The primary uses are for locking a container into place on container ship, semi-trailer truck or railway container train; and for lifting of the containers by container cranes and sidelifters.
The female part of the connector is the 7×7×4+1⁄2 in (180×180×110 mm) corner casting fitted to the container itself, and which has no moving parts, only an oval hole in the bottom. The hole is a 4.9 in (124.5 mm) diameter circle with two flat sides 2.5 in (63.5 mm) apart. The male component is the twistlock, which is fitted to cranes and transport bases. This can be inserted through the hole (it is roughly 4.1 in/104.1 mm long and 2.2 in/55.9 mm wide), and then the top portion (normally pointed to make insertion easier) is rotated 90° so that it cannot be withdrawn. The mechanism is the same as that of a Kensington lock used on laptops and portable devices, but on a much larger scale.
The maximum size and position of the holes in the connector is defined in international standard ISO 1161:1984.
Levinson, Marc (2006). The box: how the shipping container made the world smaller and the world economy bigger. Princeton, N.J: Princeton University Press. ISBN 0-691-12324-1.
