Rail slider for a cable window lifter of a motor vehicle with - a base body designed to be displaced along a guide rail of the cable window lifter in engagement with said guide rail, - a retaining bracket, which is spring-elastically connected to the base body via a base and has a latching hook at its upper end, the latching hook being provided to engage in an existing latching opening in the window pane and to be supported with an abutment surface (210'a) against the contour of the latching opening, - wherein the retaining bracket has two lateral webs and a transverse connecting element with the latching hook, wherein the lateral webs of the retaining bracket are connected to the base of the base body, - wherein a base connected to the base is arranged within a clear width (Z2a) of the retaining bracket, which base forms an abutment surface facing away from the base for a lower edge of the window pane, - wherein the ratio of the clear width (Z2a) between the inner surfaces of the lateral webs of the retaining bracket and the distance (Z1a) between the abutment surface of the lower edge of the window pane on the one hand and the abutment surface (210'a) of the latching hook on the other hand assumes at most the value 1.2, and/or - wherein the ratio of the clear width (Z2a) between the inner surfaces of the lateral webs of the retaining bracket and the lever length (Z3a) between a base-side virtual pivot axis of the retaining bracket, which results from an elastic deformation of the lateral webs in the region of the connection of said webs to the base, on the one hand, and the abutment surface (210'a) of the latching hook on the other hand, assumes at most the value 0.5, characterized in that the transverse connecting element of the retaining bracket is substantially arc-shaped, such that an inwardly pointing arc composed by radii (r1a, r2a, r3a) has no straight segments, which are longer than 0.3 times the width (b1a) of the lateral webs. - a base body designed to be displaced along a guide rail of the cable window lifter in engagement with said guide rail, - a retaining bracket, which is spring-elastically connected to the base body via a base and has a latching hook at its upper end, the latching hook being provided to engage in an existing latching opening in the window pane and to be supported with an abutment surface (210'a) against the contour of the latching opening, - wherein the retaining bracket has two lateral webs and a transverse connecting element with the latching hook, wherein the lateral webs of the retaining bracket are connected to the base of the base body, - wherein a base connected to the base is arranged within a clear width (Z2a) of the retaining bracket, which base forms an abutment surface facing away from the base for a lower edge of the window pane, - wherein the ratio of the clear width (Z2a) between the inner surfaces of the lateral webs of the retaining bracket and the distance (Z1a) between the abutment surface of the lower edge of the window pane on the one hand and the abutment surface (210'a) of the latching hook on the other hand assumes at most the value 1.2, and/or - wherein the ratio of the clear width (Z2a) between the inner surfaces of the lateral webs of the retaining bracket and the lever length (Z3a) between a base-side virtual pivot axis of the retaining bracket, which results from an elastic deformation of the lateral webs in the region of the connection of said webs to the base, on the one hand, and the abutment surface (210'a) of the latching hook on the other hand, assumes at most the value 0.5, characterized in that the transverse connecting element of the retaining bracket is substantially arc-shaped, such that an inwardly pointing arc composed by radii (r1a, r2a, r3a) has no straight segments, which are longer than 0.3 times the width (b1a) of the lateral webs.