Overstock drops the 14-inch Select-A-Firmness Twin-size Memory Foam Mattress from $349.99 to $314.99 through 7/29. Better yet, click here to activate $12 off when you pay with a new account, to cut it to $302.99. This memory foam mattress is available in three levels of firmness for your maximum comfort: soft, medium and firm. It is well reviewed with 5 out of 5 stars from 3 reviewers. Shipping is free with a new account and there is no sales tax (except UT).