Modern Design Heavy Duty Ball Bearing Single U Groove Nylon Pulley Wheel Yellow Zinc Alloy Bracket Sliding Window Rollers 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: