Hemispherical Washers are half a sphere with a hole perpendicular to the flat side which corresponds to the thread size you will use it with. They are used alongside hemispherical cups which sit together allowing for up to 10 degrees movement from the vertical.
Hemispherical Cups are cylindrical with part of a sphere cut out of one side with a hole in the center that corresponds to the thread size being used. They are used alongside hemispherical washers which sit together allowing for up to 10 degrees movement from the vertical.
BZP - Bright Zinc Plated - A 3 micron plating is applied to the steel to give a shiny finish. Although it does afford some protection this is best suited to an indoor use.