Steve, 3 Wheeler naturally on this forum.
The screens seem to be a subject of some discussion amongst owners, for the above reasons, and the 'Brooklands' seem to be the answer as they are not only made of laminated glass, but can be adjusted for height and angle to suit the driver.
I'm also a little concerned that the standard perspex screen will get easily scratched whilst being cleaned up end up impossible to see through, especially at night and when driving into the sun.
Here is a URL to one of the suppliers, I see they are happy to export to the US:-
www.vintagecarparts.co.uk/products/460-container-brooklands-aeroscreen
