Stihl TS 420 Cut-off Saw / Tools for cutting concrete and steel

Concrete is one of the strongest and most popular building materials. What can be used to cut a window or door opening in concrete? The Stihl TS 420 concrete cutter is the right tool for this task. By using a diamond cutting disc, the petrol cutter can cut through concrete blocks with ease. The compact size and low weight of the petrol cutter make it easy to cut both vertical and horizontal concrete walls.
When you add a metal cutting disc, you have a versatile tool for working with metal. The chainsaw can easily cut through metal structures of any complexity and thickness

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How do you cut concrete slab with steel at the same time with a one disc ?