A mattress that has begun to dip in the middle is usually being let down by what is underneath it. This bunkie board puts a flat, rigid layer back under the mattress so body weight is supported evenly again, which relieves the lower back without the cost of replacing the bed. The boards are built from wood planks thickened to 1.5 inches, enough to take nightly weight without flexing or cracking. It arrives as two modular pieces that connect and adjust rather than one rigid panel, so it fits through doorways and up stairwells that a full sheet cannot pass. The Oxford fabric cover is tear resistant under pressure and breathable, letting air move under the mattress instead of trapping moisture. Standard twin sizing suits bedrooms, dorms, rentals and guest rooms.