There are several places on line that sell RV matreses, and will ship to your door. Just do a search for them. like the previous member stated, sounds like yours is a regular lenghth house one. We ordered one 2 years ago, put inside opened it up and was ready to go. To make sure you can measure the lenght and width you need before placing your order. Our unit came with a "King" but was too long for my wife to manuver around. I just trimmed off the extra base lenght with a jig saw and replaced with a Queen RV Short mattress. Good Luck and Happy Camping !!!