Aqua Illumination Optic Changeover

[DBSAM]

I just ordered 70 degree optics to changeover my three Sol blues.

What is the hex head size? Is it metric?

Also, do the old lenses just fall out or are they secured in some fashion? I would like to change out the 40 degree optics with out removing each unit from my hood, is that a foolish idea?

Thanks