Material: Sturdy carbon steel body and nylon roller make sliding smooth and quiet; Easy installation: No groove required for the door, no hole drilled in the floor Size: Wheel diameter is 37mm; Suitable door thickness: 2.5cm-5cm; Practical and innovative design: The invisible rotating wheel on a vertical side not only makes sliding smoother and quieter, but also saves space.; Product Details Color: Black Size: 40-55mm*25mm*4mm Wheel Diameter: 37mm< /p> Suitable door thickness: 1.5cm-4cm 1.Small sliding wheel fixed to the wall to save more space 2.adjustable wheels made of polyurethane material won't cause scratches when the door slides 3.adjustable sliding channel for 2.5cm-5cm thickness door panel No need to drill holes in the floor, it must be mounted in the wall the smooth surface prevents the door from being scratched when sliding Simply adjust the roller to allow for different door panel thicknesses