I use a strip I cut from black carbon vinyl wrap. I find anything semi opaque isn't good enough against low winter sun.
I've been looking at these for a while.
So have done the electrical tape thing and got bored of the adhesive smearing away from the edge every time I cleaned the visor
The thing is that even if you manage to block the low sun, if the roads are damp, there's nothing you can do about glare from the road cos if you wear a tinted visor or glasses, dark enough to help, the shadows are just blacked out. Dry, mild, overcast days are the only days I choose to ride in the winter nowadays. I don't feel a moment's envy when I see a bike on the road on a shitty, slippy, grim Janaury morning.
Some of those electrical tapes have a very gooey adhesive. The kind of stuff that gets all over your fingers and then the tape doesn't stick very well either.
Good quality electrical tape = no glue issues. Polarised glasses = no road glare.....job done.