The biggest beds can breed a big dust mite problem if left unprotected. Our super king encasements are specifically made to shield extra-large mattresses and duvets from dust mites and allergens. The oversized mattress encasement fully encloses your super king mattress to stop dust mites in their tracks. We also offer a super king duvet encasement, so even your large duvet stays mite-free. With these covers, you can enjoy your spacious bed without worrying that dust mite allergies will disrupt your sleep.