Heavy Duty Needle Bearing Double V Groove Nylon Pulley Wheel with Zinc Alloy Bracket Product Overview High-quality sliding window rollers featuring a zinc alloy inner frame with nylon housing, designed for smooth, quiet operation of aluminum sliding windows and doors. These heavy-duty rollers are particularly popular in South American markets. Key Features Load Capacity: 100kg (suitable for heavy sliding glass doors/windows) Premium Materials: Housing: Transparent nylon