Unable to find a silk pillowcase, co-founder Fiona Stewart sourced the best silk she could find and wrapped it around her pillow. The results were dramatic and immediate and she felt she had stumbled upon a long lost beauty secret. What sets Slip apart is their Slipsilk™, which has been specially commissioned and made to their exacting standards using only the highest grade (6A) long fiber pure mulberry silk for the ultimate combination of shine, thickness, softness and durability.