Smooth Metal Bearings: The bottom wheel uses a more stable and heavier metal bearing. The concave wheel design is more uniform, the bearing shaft is smooth and round, and the sliding motion is scratch-free. High-Quality Material: Stainless steel plate, up to 1.5mm thick, thick material, not easily deformed, can be used in humid environments, durable and corrosion-resistant. Self-Cleaning Function: Each movement automatically cleans dust and debris, effectively preventing dust penetration and increasing durability. Suitable for cabinets and kitchen cupboards of various styles. Simple Structure: Quick-mount knob, top guide wheel with copper knob, retractable top wheel for convenient door mounting. Cylindrical shaft, horizontal rotation structure, glides smoothly without jamming. Package Includes: 2 sets of sliding wheels that can form two pulleys. It is recommended to install 2-4 pulleys per cabinet door.