Abstract: An expander mechanism to be used with telescoping tubes which might form, for example, a closet or a shower curtain rod. The mechanism has a bushing with a center threaded opening for receiving a threaded shaft of a bolt. A lock washer, which is resiliently deformable in one direction only, is attached to the head of the bolt. The bolt with the lock washer is threaded into the bushing. The bushing is then mounted on an end portion of a first tube. The first tube is slidable inside a second tube of larger diameter. When the first tube is telescoped within the second tube, an applied axial force causes the washer to deform and thus allows the first tube with the attached bushing, bolt, and washer combination to slide along the inside of the second tube, allowing the assembly of the two telescoping tubes to expand in length. Once the bolt and washer combination has been pulled through the tube in one direction and the axial force is no longer applied, the deformed washer returns to its original shape.