I like that the Box Cushion Armchair Slipcovers stretch to fit my sofa arm, stay in place and are soft to touch.  I use them with a a Box Cushion Sofa Slipcover that I love that I also got from Wayfair - it molds to the sofa cushions and stays in place with ties - fabric has a lovely feel also.  Excellent items that protect my sofa that's has heavy use.