The Hyundai DURAWING 315 is a Concentric Overburden System designed for casing of 373 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 315 is the self actuating wing bit system that works perfectly everytime.
 
Drilled Hole Diameter: 373mm
Casing Size O/D: 355.6mm
I/D: 336.6mm 
 
Major Body Diameter: 334mm
Length: 945mm
System Open: 373mm
Casing Size: 336.6 / 355.6mm
Total Weight (approx): 322kg
Hammer Type: QL120,  SD12