SUNPASS Corner Casting SPCC are the Standard ISO type container corner castings. Corner castings are the structural element of a shipping container allowing it to be connected to other containers both horizontally and vertically as well as being connected to transport modes including ship, rail and road. When connecting containers together the corner casting provides the structural connection point required for the many different types of shipping container connectors such as shipping container double ended twist locks, shipping container weldable twist locks and shipping container bridge clamps.