【Value Pack】This sliding door roller kit includes 8 rollers (4 upper rollers and 4 lower rollers). Dimensions: Lower roller: 8.5 x 8 x 7.2 cm, thickness: 2.5 mm (disc diameter: 3.8 cm); Upper roller: 4.6 x 4 x 5 cm (disc diameter: 1.9 cm). 【GALVANIZED IRON STRUCTURE 【STURDY】 The surface of the sliding door rollers is covered with a galvanized metal coating, which will not rust, even in humid environments such as bathrooms and kitchens. The sturdy doors provide increased stability compared to standard plastic fittings. Ideal for furniture sliding door accessories, often used in buildings. 【Quiet Design and High Compatibility】 The stitched sliding door rollers are made of high-quality nylon, which is lightweight, durable and wear-resistant. They ensure quiet and stable operation and reduce noise during use. The casters are equipped with an adjustable spring system for height adjustment without tools or technical skills. The sliding door casters are compatible with most European standard