· ADD STRONG, LONG LASTING SUPPORT TO SOFAS: easily and quickly upgrade your sagging sofa with our ultra strong, high quality plywood support board; adds extra support and comfort to sofas with sagging frames, cushions or worn out springs; our boards are 21.5” wide to cover more surface area therefore providing more support· ULTRA DURABLE .43 INCH THICK PLYWOOD BOARDS: unlike other brands that use MDF or particle board, ours is constructed with high quality .43” thick plywood that is naturally stronger and more durable; support board can hold up to 400 pounds· STAY IN PLACE GRIP DOTS: designed to stay in place on sofas, board features hundreds of slip resistant PVC dots on the underside; dots help grip to sofa frame and prevent board from shifting during daily use; individual board panels feature rounded corners to reduce chance of cover tearing· EASY TO INSTALL: extremely easy to install in minutes; simply remove cushions from sofa, unfold board and apply to width of sofa frame with grip dots on the underside; add cushions back to sofa on top of board· FOLDABLE AND STACKABLE FOR UNIVERSAL FIT: boards are available in standard sofa sizes for a perfect fit but can also be folded and stacked to accommodate loveseats and smaller sofas; we recommend measuring your sofa before purchase; measure your sofa seat width from left inside arm to right inside arm; this support board measures 78 inches