This is the cushion cover only! You will have to supply your own insert.100% cotton twill cushion covers with a hidden zipper. I can't wait to dip these in a bucket of fabric dye! I'm planning on trying my hand at some ombre and then finishing them with a foil heat transfer image. Cushions are hot, hot hot right now and these are amazing quality. 45cmx45cm in size. 45cm = 17.7 inches.I use a 19x19 insert inside but I am positive a 18x18 would also work. Of course this depends on the quality of your insert and the amount of 'puff' as they do vary.