Rok 5 Pack Hardware Soft Close Damper for Cabinet Doors/Compact/SoftClose Cabinet Adapter/Hardware/Hinge Polished Nickel Finish, SCD103

Can anyone comment on continued use? Are these dampers still delivering after 6 mo of use?

Do these come with the screws or will I need to buy those separately? If I need to purchase screws what size is needed?

what does this mean **works for cabinets with self-closing hinges only?

Is the Rok soft close dampner made entirely of plastic and painted with a metal type (nickel) finish? Or are parts of the dampner plastic and metal?