Designed to remove broken fasteners without jamming. 
The twist allows it to keep digging in, allowing more torque in while trying to extract a broken fastener.
Set has a combination of metric and imperial sizes

With 12mm Hex
Metric Sizes: 3mm, 4mm, 5mm, 5.5mm, 6mm, 8mm, 10mm
Imperial Sizes: 1/8", 3/16", 1/4", 3/8" 

With 16mm Hex
Metric Sizes: 11mm, 12mm, 14mm
Imperial Sizes: 1/2"

Length: 28mm

Barcode # 9322159106817