absolutely solid part with correct mechanical properties. for the fraction of the price of a Novoflex adapter you can nix go wrong and also purchase for each objective one. I have the Tokina 17mm with CY mount alpha7 run at the - skin out well. The only drawback: the inner side walls reflect despite grooves point sources of light near the edge of the picture (though with a 50mm lens), because the black paint has fallen too shiny. One tip - the three Phillips screws on CY bayonet again tighten front adapt, mine were a bit loose.
