This is a Dorian brand CA series wedge type quick-change toolpost. I have tested this with some CA holders and it locks up just fine. Please note, I believe that the Dorian badge has fallen off, however the tapered handle and red knob indicates that this is in fact a Dorian. I bought it with a bunch of Dorian tool holders as well, so I have no reason to believe this is anything else. This item is in the category "Business & Industrial\CNC, Metalworking & Manufacturing\Workholding & Toolholding\Toolholding\Quick Change Tool Post".