18″ Long aircraft-grade extension for the Drill Bit Warehouse Dry Core Bit System for Core-Drilling when using our Dry Core Bits. Also used when a long extension is needed to drill out rebar embedded deep into concrete. This Extension works with the SDS Max, Plus, or Spline adapter and with the Pilot Bit for the Dry Core bits, or used to extend the length of the Rebar Cutters as well as the Ratio Concrete Bits. Made in Germany. Comes in 11″ and 18″ Lifetime Warranty!