In the sling, the hook, wire rope, chain and other special rigging are commonly used. Lifting sucker, clamp and fork can be used as special spreader on the crane for a long time, or as replaceable auxiliary spreader hanging on the hook for temporary use. They are commonly used in multi cargo warehouses and yards to improve operation efficiency. Generally, the spreader for grabbing bulk materials is a grab which can be opened and closed by jaw plate, and it can also absorb magnetic materials such as metal chips by electromagnetic sucker. The lifting tools commonly used for lifting mobile materials are buckets and hanging tanks. Generally, the liquid steel or chemical solution is discharged by tilting or pulling the bottom plug, and the mobile materials such as concrete are discharged by opening the bottom door of the hanging tank.