Premium water mattress features 25 mil vinyl (25% thicker than most), Deep molded Feather top pressure reduction surface for greatest conforming comfort, lumbar support with 5-8-5 fiber layer waveless system - tethered to corners to prevent shifting, heater compatible bottom, bottom seams for greater durability, reinforced corners. Fits standard wood type waterbed frames. If you don't already have a frame, frame building instructions included. Strobel Waterbeds are naturally fire resistant and do not require flame retardant chemical based flame barriers like other mattresses to comply with federal fire safety regulations. This bodies are over 90% water. Strobel Waterbeds achieve nearly zero-gravity. Archimedes' Principle, proved a body floating or submerged in a liquid is buoyed up by a force equal to the weight of the liquid displaced. Thus the human body loses the amount of weight of the liquid displaced so that your body is lightened. This imposes less pressure on the body. Strobel Waterbeds go a step further with unique deep molded ''Feather top'' pressure reduction surface. The feather top surface relives surface tension and further reduces pressures to allow for true flotation sleep so your muscles and body can truly relax. Strobel Hydro-Support Waterbeds also feature reinforced corners, 4-way tethered waveless system to prevent shifting, bottom seams to relieve pressure on seams, thermally efficient heater compatible bottoms, and added lumbar support for better back support. Many people rave about the health benefits and how well they sleep on Strobel Waterbeds. Made in USA.