A guiding rail is described with a carcass rail, fixable to a cabinet carcass, a running rail, fixable to the cabinet pull-out part, a center rail slidably connecting the carcass rail to the running rail, permitting telescopic movement of the carcass rail, the center rail, and the running rail with respect to one another from a compressed position to an extended position, a blocking device, and an operating lug disposed in a rearward end of the running rail. The blocking device includes a rod, at least one first snap-in tooth projecting from the rod, a notch lever pivotally disposed at a rearward end of the center rail, and at least one second snap-in tooth associated with the notch lever. The first and second snap-in teeth engage associated components of the guiding rail such that the guiding rail is lockable in both the extended and compressed positions.