A rolling element cage for positioning a plurality of rolling elements between two rail elements of a telescopic rail or a linear guide which are mounted so as to be movable relative to each other is provided. The rolling element cage is composed or can be composed of two or more module elements which include a base module and one or more extension modules. Each module element has at least two receiving legs, each having one or more openings for receiving rolling elements, and at least one connecting section connecting the two receiving legs, the base module and the one or more extension modules being fixedly or releasably connected or connectable to one another in series in the longitudinal direction of the rolling element cage via fasteners.