The pp compression valve is simple to install but require a wrench in most cases. They consist of three components: the sleeve, nut, and fitting body. All components work together to create a watertight seal. To create this seal, you must:

Slide the nut onto your tubing.
Slide the sleeve up to the nut on its threaded side.
Put the tubing into the connector on the fitting body, and pull the nut, and then the sleeve, down so that the threads on the nut meet the threads on the fitting body.
At that point, you will screw the nut onto the fitting body.
Use your wrench to tighten the connection.
To remove the fitting, simply do the same thing in reverse. When you pull the sleeve out of the fitting body, the sleeve will stick to the tubing. If you're just putting the sleeve right back into the fitting body, or you're connecting the same tubing to a new angle-stop configuration, you can simply reuse the sleeve. If you are not reconnecting the tubing to another form of a compression fitting, you will have to cut the sleeve off to remove it from your tubing.