Size: Roller wheel width for shower door: 6 mm. Glass thickness: 5-8 mm. 4 Pack: Double shower door rollers, 4 pack, 23 mm, shower door rollers, 2 top and 2 bottom. Material: metal, zinc alloy, stainless steel bearing. No noise: Glides smoothly - easy to install and maintain. Suitable for most shower screens, shower enclosures, and steam rooms. The size is measured manually, please allow 1-3 cm deviation. Due to the different pixels of the monitor, there may be color differences, please refer to the actual product.