I can attest that the Sung Il is cast. The Grainger website says it's milled on a CNC machine. It looks like about as good an option as I have seen in an alu locking bridge, and certainly competitively priced with the Hipshot...which is the only other alu locking bridge I can think of. Of course, I haven't seen one for sale by a US seller, which undercuts price-competitiveness for me at least....