Wera Zyklop Flex Lock Extension with 1/2in Drive, The optional press-button lock system allows fast socket change and prevents tool loss. Press red to lock; press green to unlock. The extension has patented spin sleeves which provide ultra fast spin finger tightening and a patented combination of machined knurling and groove at base of tool for easier finger tightening. Length: 250mm. PTDWER003643