You will never find one of these when you need them. Buy at least three and they will come in handy, i'm speaking from experience. These are a great price and have a quality feel too. I recommend to buy three, especially if you are running any kind of dosing system.
Used this micro valve on a custom built kalkwasser doser. Allows you to adjust drip rate precisely and does not clog. Good quality plastic so it doesn't feel flimsy. Overall good product!