What kind of valves are these under the sink?

Look like some sort of cheap valve that I've never seen the likes of before. Since the line exits at a right angle and the white knobs are round I'm beating it must be some sort of washer seated valve.

To turn them off turn the white handles clockwise (right) as you you would look down on them from above. This should shut off the flow. Washer seated valves are notorious for corroding up internally and not sealing completely off.

Like the other posters here, I'd recommend that you swap them out with good quarter turn valves. You would need to shut your water off at the main to do this. It is well worth the money, especially if an emergency comes up and water is spraying all over the place under the sink.

/r/HomeImprovement Thread