Throughout your research, you may come across 4PL. 4PL essentially adds another layer of separation between businesses and their 3PL shipping providers. If a business decides to also use 4PL, then 4PL manages and arranges the 3PL services for a client. This is known as “double brokering”. 4PL is involved with all aspects of the supply chain process and acts as a single point of contact for every party involved. 3PL tends to focus on more discrete functions of supply chain operations.