Engineered well

First thing to do is put about 1/4 drop of liquid super glue at the edges of the screen. Wait a minimum of 24 hours and that little sucker will never fall out again even with aggressive cleaning. Install mouthpiece at an angle, put one edge in first then snap the other in by pushing on the mouffpiece opening. I change them regularly and keep several in a 35mm film container (remember them?) and then clean them all at once by filling container with alcohol.

Be safe!

Perfect extra mouthpieces needed for health and safety. Thank you!