The Classic Square sofa sleeper system includes engineered low-profile linkage along with body-support tubes and wires for enhanced support. It eliminates sagging and the two-ply ballistic decking material enhances durability and visual appeal. The Classic Square™ Sleeper mechanism is a heavy-duty contract/residential sofa sleeper system with a number of features and benefits to ensure comfort and durability. The Classic Square™ is considered the easiest to operate in the industry, and is engineered with low-profile linkage to keep all metal parts below the mattress line. Its all-square tubular frame construction provides a smooth and visually appealing look with improved safety (eliminated pinch points) and comfort in the seated position. The dual one-piece tubular legs also provide enhanced stability and strength, making this one of the highest quality products on the market. This listing includes both the replacement mechanism and a 6" innerspring mattress.