Thread for replacement on apparatus using G.p.I. (Glass packaging Institute) thread. These threads are used primarily on products manufactured in the United States. When a thread is designated as 20-400 it means that the diameter across the top of the threaded area is 20mm. The numerical 400 designates a specific style of the finish. The following Chart shows both the "T" and "H" dimension for use in identifying the thread. If the Chart does not contain a dimension for style or size thread, this thread is not available.