The size is L. Dimensions are listed in the last image. I purchased it and put it on my home chair once. It didn't fit the shape of my home chair, so I kept it in storage. (It's a thin high-back, so it's hard to find ones that fit.) I think it would be okay if it's a dining chair with an average back shape, but please check the dimensions. I plan to fold it flat and ship it via Yu-Packet Post.