3/8" Dr. Quick Release Locking Extension Bar, 3 pcs SetFeatures Extension with Patented PopLock (Automatic security locking system). PopLock Locking mechanism allows the user to lock socket in security position during deep compact space turning and avoid socket falling out when taken out socket with screw Material: Cr V exceed DIN Torque 3 pcs Extension set includes: 3 8" Dr. x 250mm 450mm 600mm (Length) Application Designed to provide security locking system when working in tight and deep restricted