1 What does Nickel or Black mean? - This refers to the color of the connector shell.

2 Type of Wall Plate? - Bulkhead wall plates will have HDMI on the front and HDMI on the rear.

3 What does D Series and Keystone mean? - This simply refers to the connector mounting holes used in the plate. The D Series type is a 3 hole design and connectors mount to the plate with machine screws. The Keystone type plates have Keystone holes and the connectors snap in.