An adjustable mold for direct chill casting of metals has longitudinally movable end walls which are clamped between the mold side walls during casting. Each end wall is secured to a sliding carriage which supports the end wall and allows it to be moved along the end portions of the side walls. The sliding suspender has a clamping mechanism which applies a clamping force to one or both of the side walls, the force being transversely directed through a center of the end wall. The side walls are pivotable relative to one another to allow clamping and unclamping of the end walls. Preferably, one end of each side wall is pivotable so as to transversely displace the opposite end of the side wall, with the pivoting ends of the respective side walls preferably being opposite one another across the mold.