Wonder why?. Here are the reasons… STANDARD SIZE. BACKREST COVER: fits 13.5" to 17.5". SEAT CUSHION COVER: 13.5" to 17.5". Has ties to fasten the seat cover. EASY INSTALLATION and ANTI SKID. Its all-around elastic edges will fit the seat & backing of the chair smoothly and prevent the cover from tangling and bunching up when you’re using it.
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