The hemispherical washers (BU1) and cups (BV1) provide a pivotable action when used with threaded rod. They allow a 10 degree swing in all directions from vertical and when used in pairs can provide a locked connection. Typical applications would be connecting to a roof rafter where the threaded rod needs to be hanging perpendicular to the floor or for making a ball socket on the legs of air conditioning support frames to allow adjustability for sloping roofs.
