What is a waterbed insert? If you have an old time waterbed and you would like to put a conventional mattress inside an old wood waterbed frame we can help. Your new mattress in most cases made to order in 3 business days plus ship time to your location. The process to convert a waterbed to a regular mattress is fast, easy, and best of all in most cases you keep your bed just the way you have it: drawers, furniture, bedding etc. no matter what type of mattress you choose: Coil spring, memory foam, latex, etc. Our replacement mattresses are specially sized to fit your California King, California Queen, or Super Single bed for easy making and most are 2-sided and flippable to last you longer. Click on each model below to learn more details about construction, firmness, and prices.