John, Clearview Shields makes direct factory replacements for both the Roadster Screen and the Summer Screen (Triumph's only factory screens). They are available stock to up to 4" taller. I don't know of any other company that makes screens that exactly fit the Triumph hardware. The Clearview ones are actually higher quality than factory and resonably priced.
The only problem is that Triumph did not design the mounts to be easily or quickly removeable. Check out the Clearview website:
Clearview Shields - Triumph 
