A tool includes a tool bit, a handle and a locking device. The tool bit includes a working head formed at an end, an insert formed at an opposite end and at least one annular groove defined in the insert. The handle includes a grip formed at an end, a socket defining a cavity for receiving the insert of the tool bit and a joint via which the socket is connected with an opposite end of the handle. The locking device can lock the insert of the tool bit in a releasable manner. The locking device includes a tunnel defined in the joint so that an axis of the tunnel is parallel to that of the cavity. A latch defines at least one notch. The latch is movable in the tunnel between a locking position and a releasing position. The locking device includes at least one truncated conical hole through which the cavity is communicated with the tunnel. The at least one truncated conical hole includes a first end at the cavity and a second end at the tunnel. In the at least one truncated conical hole, the first end is smaller than the second end. At least one ball is trapped in the at least one truncated conical hole. The at least one ball is pushed partially into the at least one groove by means of the latch in the locking position. The at least one ball is allowed complete removal from the at least one groove in the releasing position. Link to USPTO.