The Hyundai DURAWING 90 is a Concentric Overburden System designed for casing of 125 mm diameter holes through varying formations into bed rock.
The wing bits are enclosed making them the most professional & efficient system on the market today as they are not exposed to "clogging" in loose overburden material while drilling down to the bedrock.
When the drilling starts, the bit wings protude utilising a unique cam sliding mechanism. The key feature of the DURAWING 90 is the self actuating wing bit system that works perfectly everytime.
 
Drilled Hole Diameter: 125mm
Casing Size O/D: 115mm
I/D: 101.6mm 
 
Major Body Diameter: 101mm
Length: 411mm (IR3.5)
System Open: 125mm
Casing Size: 101.6 / 115mm
Total Weight (approx): 13kg
Hammer Type: IR3.5