Do I need to use the retainer bar that was provided? August 12, 2020 14:04 The retainer bar secures your mattress in place while using the Adjustable Base. Related articles How many positions can the Adjustable Base move into? What is Zero Gravity (ZG)? Can I use a bed frame with my new Adjustable Base? Can I assemble the Adjustable Base on my own? How do I use the Adjustable Base with a King or California King mattress?