1.material of wheel is nylon which is anti-abrasive. 2.materisl of hull is iron with galvanized. 3.used for door&window 1.The material of wheel is nylon material of the hull is iron with galvanized.2. this kind of roller mainly used for door & window. and which is easy to install and strong enoughOur company specilizes in accessary for door & window . and we have been in this line for many years. ...
