... blue zinc plated, Top plate swivel housing ,with Precision double ball bearing, 5.8mm thickness pressed steel .4.Top ... to Pvc,rubber ,nylon ,pp ,tpr ,cast iron,high-heat resistant material ,conductive wheel7.Applications: supermarket, display racks ... industrial, etc. 8.Assorted colors (optional)High shock absorption/High abrasion resistance/ High Stain resistance.[Detailed Setting Explanation] Wheel ...