In the table mentionning the specs of each model, the ratchet head size for the AT-30 model is announced as being 1/4", therefore accepting directly 1/4" sockets. In fact, the actual head size is 3/8", with an adaptor supplied. Is it simply a matter of choosing the desired ratchet head, since they apparently are interchangeable? In which case it might be adequate to point it out. Apart from the above remarks, the torque wrench meets its description and indeed appears to be of the quality I was looking for.