The terminology used to describe the majority of foreign threaded fittings can be confusing to some. Metric fitting is a term describing a number of foreign threads including BSP, JIS, Kobelco, Komatsu, and Metric, even though some of these have imperial dimensions. Metric threads, however, refers to a specific type of foreign thread and is part of the Metric fitting category.

Hose/Tube Side vs. Port Side:

When fittings are classified, they are usually done so tube or hose side first, meaning that the end connecting to a hose or tube is typically listed first. The port side is usually listed second.

Thread Form vs. Thread Pitch:

When identifying fittings, another important factor to look at is thread form and thread pitch. Thread form refers to the angle (in degrees) that exists between adjacent flanks of a thread. Thread pitch however, refers to the distance measured between adjacent thread crests.