Product Information: Made of iron, strong and durable, high strength, good stability, and small creep. Good wear resistance and chemical stability, can be used for a long time. Product Advantages: The double-layer and its structure ensure the stability and smooth running of the gate. Reduces vibration, reduces noise, and ensures smooth operation. Perfect for indoor or outdoor use. WIDELY USED: Uses: Replacement parts, gate wheels, sliding fences, sliding window bearings, 3D printers, shower screen bearings, washing machines, dog gates, garden gates, wire guides, etc. Suitable for professional (industrial) or DIY projects. Easy to Use: Easy to install and use. Suitable for experienced and non-expert users. The diameter of the wheels is 15 mm, the total height of the wheel is 28 mm, and the depth of the U-shaped groove is 4 mm. The U-shaped groove fits perfectly with the inverted groove. Precautions for Use: The maximum load capacity is 40 kg. Iron is the main material, do not use it in a humid environment.