Living in the US and looking for a hard Korean ‘yo’ mattress? I searched the US websites with little luck. I did find one site but 200 bucks for a Pororo mattress pad seemed a little expensive. Check out the Korean website Gmarket, you’ll find them there. Some of the sellers do international shipping. It helps if you know a little Korean. Although the site claims to have an English version it’s not fully in English http://english.gmarket.co.kr