Product Code: F0790 Amtech 3pc Metric Step Drill Set Titanium Nitride Coated High Speed Steel Ideal For Aluminium, Brass, Copper & Mild Steel The Depth Diameter Is Clearly Labelled On Each Step Quick Change 1/4\” Shank Complete With Nylon Storage Bag Set Includes The Following: 9 Step Bit: 4-20mm 13 Step Bit: 4-12mm 15 Step Bit: 4-32mm