What is quest plumbing?

You may mean Qwest fittings. (yes, with a 'w' not a 'u') This is a range of plastic Plumbing compression fittings to fit many different pipes. They have an 'O' ring and a gripper inside a large nut to tighten onto the pipe. -Very hot item when they came out 20 or so years ago, now a little old fashioned compared to Sharkbite and similar fittings.