Variable thread tie screws The variable thread tie screw is designed to anchor all categories of railway track on wooden ties. Benefits : Improved attachment of the rail fastenings to wooden ties.Increased durability of the wooden tie.The effective tightness of the fastening is maintained over time compared with that of an ordinary thread tie screw.Non-loosening under the effect of vibrations.Waterproof : avoiding the penetration of damp, which causes the detoriation of wood Range of avalaible models: