ELORA 408 Step Arbor for Expanding Copper Tubes (ELORA Tools)ELORA 408 Step Arbor for Expanding Copper Tubes (ELORA Tools) The STEP ARBOR 408 ELORA Tools is designed for precision drilling. Using high quality materials and a sophisticated engineering process, the STEP ARBOR 408 delivers an accurate, consistent hole size every time. With precise measurements and a robust construction, this is an ideal tool for professional and personal use. for expanding copper tubes black, made of special steel Refer to Chart