Abstract: The invention aims at sliding runners comprising two sectional irons 1 and 2 mounted so as to be able to slide longitudinally one along the other through the agency of ball-bearings 3.The lower sectional iron, in the form of a U, comprises two vertical flanks 5 extended outwards by bent-down parts 6 in the shape of angle-irons, and the upper sectional iron 2, in the form of an inverted U, comprises a top 10 and two vertical flanks 11 extended inwards by horizontal ledges 12 extending under the respective bent-down parts, each ball-bearing 3 being compressed between a bent-down part and the opposite walls. Rigid bracings 19 are inserted between the flanks 5.Applications: longitudinally adjustable supports for front seats of motor vehicles.