Heavy Duty Ball Bearing Double U Shape Nylon Pulley Wheel High-quality zinc alloy inner frame with nylon housing sliding window rollers designed for smooth, quiet operation of aluminum sliding windows and doors. Product Attributes Attribute Value Material Zinc Alloy Housing Load capacity 100kg Wheel Color Any color Style Modern design Type Sliding Door And Window Rollers Function Quiet operation Key Features Load Capacity: 50 kg (suitable for heavy sliding glass doors/windows