@Jake 10 ,,,,I think you were asking me a similar question about application
For the Loctite Glass Glue I use 2 drops and pressed down on the glass circle hard to squeeze out any air bubbles. I then used ~6 wooden toothpicks to smooth and remove any excess glue around the edge of the circle. Since it's just a gauge reader glass, it sits quietly on the bottom of the mask lens and doesn't interfere or block any of my vision when I'm scanning side to side (I'm a bug hunter). When I check my gauges, I just keep my head level and look downwards with my eye to perfectly & easily read my gauge (pro plus 2).