Rohm PRIMA heavy industrial plain bearing chucks are widely used for stationary and hand operated percussion drilling machines. These industrial quality chucks have fully hardened and ground working components which offer exceptionally high accuracy, gripping power and durability. The Rohm PRIMA 20mm Keyed Drill Chuck, with female mount, JAC3, heavy industrial plain bearing chucks, are widely used for stationary and hand operated percussion drilling machines. These industrial quality chucks have fully hardened and ground working components which offer exceptionally high accuracy, gripping power and durability. Specifications:Capacity: 20mm.