[STRONG & STURDY] Made of high-quality steel with premium nylon roller wheel and Gcr15 roller bearing, the surface is black matte, High strength industrial grade tracks and pulleys can easily hold 220lbs loads,anti-corrosion and anti-rust.Maintains its beauty and longevity for many years. [Easy to Install] Warning: To ensure that the door can be fully opened and closed, the distance from the door edge to the hole of the door hangers is 1-2/5". The door shaft should be perpendicular to the...