Abstract: An extensible article of furniture suitable for use as a convertible sofa bed or an extensible bed having a pair of substantially identical frame members with end boards and side rails being interlocked with surface slats affixed to the side rails of each frame member and being alternating with one another to form a slat surface of substantial rigidity providing suitable support for sofa and bed applications of the unit. Each of the frame members may provide four-point support from a supporting floor and contains markings for ease of selecting the desired positions of the frame members for use as a sofa or a bed of particular size.