Disclosed is a linear guide unit, comprising a guiding carriage (2) that can be moved in the longitudinal direction on a guide rail (1) and a length measuring system provided with a measuring head (3) that cooperates with a material measure (4) arranged parallel to the guide rail (1), wherein the material measure (4) is arranged in a hollow body carrying said material measure (4), the hollow body being located at a distance to the guide rail (1) and being mounted at its ends.