Material: 45# high strength steel, colorful zinc plating, 204.1 kg per load Dimensions: 5.6 cm (L) x 3.2 cm (W) x 4.1 cm (H), wheel diameter: 3 cm, wheel width: 2.5 cm, U-notch width: 1.5 cm, U-groove depth: 0.8 cm U-track wheels are used in a variety of applications such as sliding doors and mechanical trolleys, etc. Built-in 2 ball bearings, making it slide with good performance. 1.7 cm round tube can be used as a track Package: 4 pieces of U-track wheel