I don't know other than he said floor jack or engine hoist, so in my mind it is that tiny little wing nut per say valve that when you go to go down under a lot of pressure say a whole front or rear of a car or a big block on a hoist with transmission and you crack the valve to let it down it jumps down the first several inches. scares the crap outta me at times. but I usually just tighten it a little and then when I go to lower it it seeps out and goes down....smoooothly. LOL