Heavy Duty Needle Bearing Single U Groove Nylon Pulley Wheel Zinc Alloy Housing Aluminium Sliding Window Rollers High-quality zinc alloy inner frame with nylon housing sliding window rollers designed for smooth, quiet operation. Product Attributes Attribute Value Material Heavy Duty Needle Bearing Single U Groove Nylon Pulley Wheel Zinc Alloy Housing Aluminium Sliding Window Rollers Load capacity 50kg Wheel Color Any color Style Modern design Type Sliding Door And Window