After reading all the posts about all kind of stuff as diffusion film I’ve decided to try something myself.
I had few “iphone matte screen protectors” from ebay lying around and I had Tank007 TK-568 with annoyingly ringy beam. I decided to give it a try and it worked great! It applies perfectly, no bubbles, no artifacts. The rings almost gone, barely seen on white wall, unnoticeable in “real life”. I’ve tried it on my Convoy L4 as well, the “flower” shaped corona it had is now a perfect circle. Other than that it has very little effect on the beam - the hotspot seems to be of the same size and still well defined with slightly blurred edges. I have no way to check how much light it blocks, but didn’t notice any difference. The led can still be seen through the lens, it only looks little “foggy”.
No pics here, it’s impossible to catch it with iPhone camera 