Here is the thing. Today I asked a shifter kart guy if they race in the rain and if so what do they use for their visor. He told me that they use RainX, as long as your visor does not have a tinted “coating” like those reflective visors; it is safe. The thing is most visor have a UV “coating” on them and I am not sure how that would react with RainX; That shifter kart guy had all kinds of sponsors so getting free visors will not be a problem for him. So idk, don’t feel like risking my SA helmet visor as they cost $70 to replace.
By the way, thanks for the info on that linked product.
Second that.