Under- the-Hook Components Because products and materials to be moved are of unlimited shapes and sizes, a simple hook is not usually adequate to engage the load. This device must be designed to accommodate the shape and size of the material it will move. Under-the-hook components are devices that are independent of the crane, carrier/trolley, and hoist hook. They are made to lift and transport materials safely and efficiently. There are a wide variety of accessories available to match the needs of a particular operation.