Metal Threaded Inserts Heavy Duty Tube Size Tube Gauge Thread Reference Tube Size Tube Gauge Thread METAL All metal range of steel tube ends. Extra Long Tube Size Tube Gauge Thread Length Reference HEAVY DUTY Range of heavy duty plastic inserts. Fitted with non-corrosive metal threads. Ideal for use with our Conveyor Feet as detailed on Page 18. EXTRA LONG Range of heavy duty plastic inserts. Fitted with zinc plated metal threads. Suitable for use with castors or heavy duty feet. Additional sizes available to special order. TELEPHONE ORDERS PLEASE CALL 0116 - 2764987