The Hyundai DURAWING 280 is a Concentric Overburden System designed for casing of 340 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 280 is the self actuating wing bit system that works perfectly everytime.
 
Drilled Hole Diameter: 340mm
Casing Size O/D: 323.9mm
I/D: 301.7mm 
 
Major Body Diameter: 300mm
Length: 774mm
System Open: 340mm
Casing Size: 301.7 / 323.9mm
Total Weight (approx): 213kg
Hammer Type: QL80,  SD10