These pillows are so large a king size pillow case will not fit. Not a single pillow case I have tried will fit. The pillows are about 4 inches thick and this makes a 20x30 pillow case too tight to release the foam so you can rest properly. This makes the pillows too hard and compacted. I have written the company to no avail to find the proper size pillow slips. These pillows are nonreturnable. Do not waste your hard earned money on this product!!!