WESTINGHOUSE LIGHTING 70113 4" Cross bar,

I P Carded Threaded 1/8" IP = IP stands for "iron pipe;" The term "carded" refers to an item that has been attached to cardboard. (Threaded steel tube, often brass-colored, is a key component in most lamps.) The standard size is 1/8 IP, which is plated and referred to as "lamp pipe." The IP stands for "iron pipe," and the sizes are based on the Briggs Standard of Wrought Iron from the nineteenth century. Dimensions of iron pipes, as well as seamless brass and copper tubing.