Let me try this again. I have found a latch looking like thing under my kitchen sink labeled nibco 580. What is this?

As far as I know, Nibco 580 refers to a ball valve that may be with or without a latch. The latch is there to prevent you from accidentally closing water supply to plumbing fixtures it feeds.

Score one for Milo. NIBCO is the brand and 580 is a ball valve, Cheers, Tom

As stated above, the Nibco 580 is a ball valve. In other words, it is a shut off valve that should shut the water off to either the hot or cold water to the kitchen faucet, the dishwasher, an icemaker, or even an outside faucet if the shutoff is connected to a pipe going out the wall.

More questions? Let us know, OK?

Mark

Re nibco 580, thanks all. I kind of thought this is what it is. When I had an outside faucet added, the plumber (and this was a plumber, not someone just saying they are) put this in place. Handy little thing I would say. It must be nice to have the knowledge all of you do on a subject which has always been of such interest to me since I was a small child. I would see my Dad (who could fix anything) tinkering around with "stuff" such as plumbing and would be at his elbow asking "and what is that and what does it do?" Needless to say, I really did not pay that much attention to the answer, or I would be a lot more versed today!

Hey Cat! Back again I see.
Is this what the plumber installed so you can shut off and drain the outside hose bib? Once you shut the water off to the hose bib and open it how do you drain 6the water out of the pipe from the hose bib to the stop? If so I would have installed a valve that's made for the job. It's calleda stop and waste valve, (see image) This allows the water to drain out of the pipe so it doesn't freeze. Next spring close off the little drain thingy, turn on the stop and close the hose bib and you're back in business. Just thought I'd bring that point up. Cheers, Tom

Tom, you got me here. I think I remember he said it was in case I wanted to turn water off to sink faucets etc.without having to go to the main? That being said I may be entirely incorrect. The picture of the faucet in your attachment looks just like the faucet I have, however, it does not have the stop and waste thing which is white. I got a "back flow" attachment from hardware store to stop back flow from hose into water line whenever I spray any "chemicals" from spayer attached to hose. I do not know if what you show in the picture and the back flow are the same or two separate things. In the winter, we cover the faucets to prevent pipe freeze.

Ingot the impression that this was added to your outside hose bib.
I kind of thought this is what it is. When I had an outside faucet added, But if it were to shut the water off to the sink I understand. Hope everything's going OK and have a great weekend. Tom