These sliding shower door top bracket roller assemblies are constructed of extruded aluminum and come in a bright aluminum finish. They feature round edge plastic wheels and have steel ball bearings to provide for long-lasting, smooth operation. These types of top hung roller assemblies are designed for use with sliding glass shower doors that do not use a frame. Installation tip: to prevent glass from slipping out from roller assemblies, follow the installation instructions which require the application of a small amount of clear silicone adhesive (RTV-108) and a 24-hour dry time prior to hanging/using doors again.