It is used for opening and closing operation of the air hose by hand. It is useful for work that opens and closes by hand without going to the original valve air which is not very high pressure. I think that it is a good product that is also excellent in sturdy construction and design. It is still better if it is a bit cheaper.
Although it is displayed, it is difficult to judge at a glance which side should be matched when opening and closing, it is easy to confuse. It seems to be caused by a structure that is almost symmetrical (compared with the company's product 34883782 BVU 6 - 6 etc.). There is no problem in performance.