comments:
kalel3000 posted on r/harborfreight2w
Get the Pittsburgh but also get valve like this so that after you vaccum out your system, you can shut it at the end of your hose, so you dont introduce air into the system when you go to switch from the vaccum pump to the refrigerant cans. Mine didn't come with one, but I bought it awhile ago, not sure if the newer ones have one or not.