Heavy structure: Our trolley components are made of high-strength solid steel, impact resistant, galvanized, and can provide anti-rust and anti-corrosion protection. It also has a solid bearing steel pin in the strut channel Safe and stable performance: the four-bearing trolley assembly has welded bearings and pin shafts, providing greater stability for safe use. It uses deep groove ball bearing to ensure that you can operate smoothly without any noise Long-term use: Each package is equipped with two beam trolleys, achieving a proper balance in quality, durability and performance. They provide low noise operation and are galvanized to provide smooth opening/closing even in the long term We support you: If you have any problem with the wheel of car component, please tell us, and we will help you quickly solve it to ensure your complete satisfaction. Please note: It is recommended that you use the pillar channel horizontally