I added the Carbon Spider carbon fiber visor [from JW Stephens] to my Catlike Helmet. The visor gives added sun & rain protection, although I should not need much of that given the fairings and panels that will be used on Fargo, my quadricycle.
In the past, the sun has been annoying due to the recumbent cycling reclined riding position.
I choose to modify the visor for the fit I want on this helmet. I use no straps or ties. I used adhesive tape, glue and black Silicon to mount the visor on the helmet. It will not come off from the wind. I am pleased with the results.