The KoverRoos® Tyvek Deep Seating LoveSeat/Settee Covers need to breathe so that moisture can escape, keeping mold and mildew from developing under the cover. KoverRoos® Tyvek Deep Seating LoveSeat/Settee Cover use technologically advanced materials that are one-way breathable - so moisture can evaporate right through the fabric, but water, dust and dirt can't get in. Light weight means our covers are easy to use - no struggling to get them on and off. Also, these patio furniture covers are able to handle temperatures from -100 degrees Fahrenheit up to +240 degrees. This particular cover comes with a u shaped hook/bungee system (set of 4) attachment system in order to secure the cover in harsher weather conditions.