This 1-1/2" Hex Boring Bar adapter is 11" long and entire unit is 17" in Length. This can fit Ammco or be adapted to fit other brands of Brake Drum Turning Lathes. We think this is maily for very Large size Brake Drums from a Semi-Truck Tractor Trailer when machining them on your Brake Lathe or regular Machine Shop Metal Engine lathe. The Lower part of the Boring Bar Clamp Head is casting number C7693 and the upper Clamp is B7694 and looks to hold another 1-1/2" hex boring bar or possibly a large round unit. This is a very hard to find unit and this is the only one we see out there for sale.We are still going to keep our price responsible and low shipping cost. Message with any questions. We do accept returns, but buyer is responsible for shipping.