SDSET-1 – Unikut 3Pc Spiral Flute Step Drill Set-4-30mm The Titanium Nitride coating significantly increases the tool life by providing the following benefits: • Increases surface hardness to 85HRC • Ceramic surface reducing friction by up to 30% • Especially resistant to cold welding. • Suitable for cutting a wide range of materials.** Set Contents: SD4-20mm SD5-25mm SD6-30mm **Will cut Stainless Steel however Stainless will reduce the edge life of your cutting tool.