- Material and removable cover The mattress filler is made from cotton-linen, providing a very comfortable feel. The cover features a zipper design, allowing you to easily remove it for replacement and washing. - High-density foam for long-lasting shape It uses high-density foam that retains its shape over time and remains soft enough to provide stable, premium comfort for the gap. - Gap filler design and compatibility Designed for the gap between the mattress and headboard, for mattress extensions, along wall edges, or between two mattresses. Our wider mattress gap filler can help you sleep more soundly and make your home feel more comfortable. - Versatile use This headboard cushion can be used in full to enhance practicality. It is not only a long gap filler to prevent items from falling under the bed, but also a comfortable headboard pad/cushion on the bed and an under-bed blocker for pets.