Amazon offers Queen Sleeper Sofa Support Board for with free shipping.

Product Description:
If you're tired of waking up with aches from uncomfortable steel bars poking through your sofa bed mattress, LAVEVE’s Sofa Bed Support Board is the perfect solution. Our specially designed boards help eliminate sagging and provide stable, even support for a better sleep experience.

• Premium Hardwood Construction – Made from thick, solid hardwood, our support boards are built to last. Offering superior durability and strength, they provide reliable support, unlike flimsy plywood options. The natural, eco-friendly material ensures a sturdy, long-lasting solution for your sofa bed.
• Thick, Durable Nylon Fabric – Wrapped in high-quality, heavy-duty nylon, the board is slip-resistant and highly resistant to wear and tear. This durable fabric ensures that your board stays securely in place, while also adding a smooth, comfortable surface.
• Smooth, Safe Edges – The rounded corners and edges are carefully sanded to ensure safety and comfort. With no sharp edges to worry about, you can enjoy a secure and comfortable support system every time you use it.
• Space-Saving, Foldable Design – The five-piece foldable design allows you to easily store the board when not in use. Simply fold it up and tuck it away when the sofa bed is collapsed, saving space and ensuring ease of use.