DEWALT 10mm 1/2" x 20UNF Metal Key-type Drill Chuck through-hole for clockwise and anti-clockwise rotation. 
Slight intermediate sizes primarily for hand-operated percussion drilling machines. 
With taper mounting respectively thread mounting impact resistant. 
The versatile applicable model has proven itself for decades, especially on hand-operated drilling machines and impact drilling machines. 
Suitable for DeWALT and other makes of drills

Features and Benefits:

Primarily for hand-operated percussion drills.
Taper mounting respectively thread mounting impact resistant.
Versatile applicable model.
Through-hole for M5 or M6 security screw - clockwise and anti-clockwise rotation

Specification:

Size - 10
Clamping Capacity - 1.0-10mm
Mount - 1/2”-20UNF
External Diameter - Ø34.5mm
Length Open - 49.5mm
Length Closed - 61.0mm
Key Size - S2A