The lens fits safely inside the goggle outline, shielding your eyes from paintball effect and spray.
Lenses can come as a single sheet or double sheet (warm lens). A single sheet lens is a one-piece lens that has an anti-fog covering added albeit less demanding to keep up and less expensive these are inclined to fogging.
One other essential thing is the power. If you plan to install your stainless steel soap dispenser in an area that’s not wired for outlets, make sure you buy a unit that is battery powered so it can be used in places where there is no direct power supply. It would typically require standard AA batteries.