Used for sliding doors. Single Ordinary SD Roller, Double Ordinary SD Roller, All Nylon Single Roller, All Nylon Double Roller, Single Steel Roller, Double Steel Roller, Tension Roller, Screen Roller 100% Brand New and High Quality. 1. Screw hole workmanship precision, clear lines. Insert the screw into the hole to attach the tab. 2. Fully furnished, save time to go to the hardware store to buy accessories, easy to install. 3. Steel material, wear-resisting compression, smooth sliding, and flexible operation, while being smooth and quiet. 4. Built-in high-precision and precision metal bearings make the suspension wheel balance in its activities in the load-bearing state. Please read before adding to cart! In the case of not having the brand in stock, the seller will either inform you or will put a different brand but the same product. Usually the product given is of a higher quality and of a higher price in replacement of the out of stock order. As we hope to please the customer! Size (Length & width) 7.5cmx3.5cm