Two-three tier racks are used for bulk storage and order picking of smaller units or components such as non-palletized goods, cartons, bins etc. The storage system is a lot more efficient as a great floor space is used in this.
Two-three tier racks system make a better utilization of the warehouse height and hence, the floor is free from disorganized goods. The process of order picking and is also smooth along with a well-organized storage systems.
Stairs or lifts are used to connect or access the different tiers.