The fly screen options for an ET are limited.
I fitted one from a Vespa S part number 655523.
Obviously it's not a close seal round the headlight but it does the job and I prefer the look of it to the ET options.
I found someone in the U.K. selling new old stock for £75.
1st pic off the internet as I didn't have one from the front of it fitted to mine. Fits without any modification.
The other nice upgrade I did was to fit LX mirrors. It's not just cosmetic, they work better. Primavera, GT mirrors work also.
One fits straight on, the other I bought an adaptor from beedspeed in the U.K.