Features: Trolley assembly is making of strengthened carbon steel and steel, impactresistance, hard to break, fade, corrosion, withstands long terms use. The bearing trolley roller is safe, with tight connection and stable performances can ensures smooth operations and reduce noise. Forgeds by tight process, the is smooth and of burrs, with uniform stress, beautiful appearance and smooth design. Trolley assembly is suitable for a wide ranges of different usage is for mounting on a ceiling trolley systems or electric lifts, you can also use it in DIYer projects according to your actual situation. The 2 wheel trolley assembly roller is galvanized to ensures the rustresistance of the wheeled trolley. Smooth , good coordination and high hardness. Specifications: Component:Stainless Steel Size:As Picture Shown Color: Silver Usesage: Can be used for family activity door, wardrobe cabinets, large iron door, curtains, automation equipment pulley The aperture of steel plate is about -9/16"/14mm, and the thickness of steel plate is about -1/4"(6mm). They are suitable for 1-5/8"/4.13cm wide and all column grooves of 1-5/8"/4.13cm or higher. Package Includes: 2Piece Double Bearing Trolley Assembly note: ①.Please allow 1-2cm errors due to manual measurement, make sure that you donot mind befores you order. ②.Due to the differences between different monitors, the picture may not reflect the actual coloring of the item. Thanks for your understandings.