Threaded Bar Studding Threaded Stud Auto Black Sizes from M4 to M20. Zinc Plated Steel Fully Threaded Rod Threaded Bar Stud. This sale is for 1 piece. Various Thread Options Available, Please select from Drop down Menu. Length : Approx. 300 -305 MM (12" Long) Finish: Yellow Zinc Plated/ Auto Black. Material: Mild Steel