A latching mechanism for coupling nestable drive shanks of a tool includes a housing presenting a locking pin movable between a normal locking position and a release position. First and second bias means cooperate to urge a free end of the locking pin in extension outside the housing so as to extend between aligned shank apertures and join the same. Upon user disengagement of one bias means on the locking pin, the locking pin is urged to a release position towards a location within the housing so as to withdraw the pin from the aligned apertures. The latching mechanism enables drive shanks to be connected at user selectable lengths therebetween.